Do you have insurance? If so go to your Doc and get a referral to an ortho and have an MRI done. Sounds like a rotator cuff tear potentially. If so alot of guys bounce back 100%...I could type for days(not really because my right rotator cuff is gone) about how rotor surgeries can go bad and it can lead to life altering circumstances.....extreme chronic pain. extreme phys limitations etc. Lets hope you have a strain or at worst just a partial thickness tear. Best wishes bro and don't do ANYTHING until you know you are 100% OK..just rest and ice...don't try stretching or to increase range of motion until you know whats up inside your shoulder.

I hear a lot of good advice. I'll add ART or massage. I prefer ART. You can't chase the knots out of your upper traps or most of your shoulders with a foam roller. Someone has to manually work out the knots.
stiff and knotted muscles throw your shoulder out of alignment as much as underdeveloped supporting muscles do.

So hows the shoulder feeling now? I had a similar problem a year ago and I was told to rest. I came back too soon and hurt it worse. I had to drop weight for a while and build it back up after the pain went away. It seemed like forever but I was 100% after 4 months or so...
I make sure I warm up and stretch before I lift anything now. Injuries Suck the big one.

Bro we are the same age and have had almost an identical experience in one instance.
and it was ONLY day in previous 5-7 years of training where I decided to skip my stretch and warm up including internal and external rotation on rotator cuff.
this sounds like a strain of one of the three muscles that encapsulate joint and allow for all the movement of the joint.
the bicept tendon also travels through this area.

If its higher on delt then rotator cuff injury prolly it.
slight tears are not uncommon and you can diagnose this yourself.
sounds like you are alsoready getting well so I just recommend if you dont already to do more warm ups for shoulders.
COming of shoulder recon surgery 20 years ago I dont play games with warm up of rotator cuff anymore except the one instance where i felt what you felt.
I laid off the shoulders for 1-2 weeks and went back lighter and issue never surfaced again.
A complete tear of rotator cuff and you would not be able to lift arm above you head with thumbs inverted pointing down in front of you.

Had a similar experience. I have no idea whether it was a ligament, tendon, or muscle pull. The pain was located in a very small spot deep within the front delt. It happened the same way yours did--going heavy on the flat bench.

It took forever to heal, about 14 months. I first took a month off, which did little. When I went back to the gym I stopped doing flat and incline bench, but did do well on the decline bench and on a cable machine.

I stopped going deep, only going until my upper arms were parallel with the bench.

I also had to put away my ego and drop the weight way down and increase reps.

You are a lot younger than me so hopefully you will heal faster. Good luck!

I have problems with both shoulders. It really really sucks and limits what I can do. I had to totally revamp my training. It just wasn't beneficial for me to lift heavy and make great progress and then inure my shoulder and have to take 3 months off. This was happening very frequently. What I did was first really focused on warming up my tendons and rotator cuffs before every workout except for legs. I do external and internal rotations with the cable machine. Next I had to stop lifting heavy. Really bruised the old ego lol. So Instead of repping the 100lb dumbbells for flat for 6-8, now I grab like the 60 or 70s and do very very slow controlled reps for 10-12. Making sure I feel every portion of the rep. I really had to leave my ego in the locker room and it sucked at first. But honestly I think I have gotten better development overtime doing the movements like this. Shoulder problems really suck man I know all about them. My best advice is to drop the weights a lot, and slow down your reps, like 3-4 second negatives, and don't lock out at the top. You should be able to recruit the same muscle fibers, but save your joints and extend you lifting career. No point in going hard and busting your ass for 6 months and then get injured and spend 3 months out of the gym,. Then you lose a lot of what you gained, and then spend the next few months when you finally get back into the gym working back up to where you previously were. And my last piece of advice is don't rush back into to gym. Let it heal and then very slowly work your way back into it.

Had a similar experience couple weeks ago day after squats. I was leaning on the couch and when I got up it just tweaked. Felt like a tendon got all flipped around in there under the front delt.
Hurt when I raised my arm up straight. did a week of NSAIDS and ice every couple hours. Still feels a bit off but back to lifting heavy with no pain. Apparently its called a shoulder impingement. There is a narrow path where a number of tendons and nerves connect and if it gets inflamed or tweaked it can be a real bitch.

Look it up, somewhat easy to diagnose. Hopefully your only out for few days. I lifted what didn't make it hurt till it was better and just iced it like crazy. Celebrex is good, there is also an Ibuprofen with argine thats a very effective anti-inflammatory too, not sure if you need a script for those, prob if your in the States I would assume so.

Lots of things to consider.

Make sure your taking animal flex and some. Boron.
Are you taking anything to promote healing right now?

You might have to say Welcome to the world of either tendonitis or tendonosis. I developed tendinosis later on in life; sometimes I have to "rush" through working out before the pain in my arm cripples me and I cant even lift a pencil. After numerous injuries I sustained my Doc told me it is now a permanent friend of mine.
Have your Doc check it out and cross your fingers.