It's the cough medicine bro, many drugs do this including anti depressants, and opiates. When I was an opiate addict I used to lay into girls for hours they would be shaking from multiple orgasms, and I would still be rigid as hell, I'd rarely bust one. Didn't mind though cause they told other girls about it lol.

The term is called "Anorgasmia" and while it is more prevalent in women it can happen in males (3-5% iirc) Right now they really don't know the wheres and whys as to how it happens, although it is tied in at times to anti-depressants. SSRI-SD has been known for sometime... prozac, etc will kill sex drive in some people. Symptoms include no or low sex drive, loss of sensation on the sex organs, and difficulty having an orgasm among others. They are now recognizing PSSD (Post Ssri Sexual Dysfunction). Basically its where the dysfunction continues after stopping use of the SSRI anti-depressant. The reason I bring this up, (A overly SIMPLE description here) is SSRI's work (and cause SD issues) by affecting dopamine levels (it gets more complicated, but this is the simple explanation). Robitussin has been shown to affect the levels too (Robo-tripping). It is possible that after being sick and all the nyquil and robitussin you may have levels out of whonk or receptors not receiving. Going back to the PSSD, the dysfunction runs different courses. With some it clears up in a relatively short time, others it doesn't clear up at all. There is information that some meds will help to a degree.. Caber (.125mg/d), Amantadine (200mg/d), Yomimbe, and Gingko-Biloba have shown promise with the issue. Caber will also help with the wood to, in addition to affecting the refractory period (time to recharge between rounds). While some may think it would be a wonderful thing to be able to go hours on end, I understand where you are coming from. It's fun at first, but after several years it sucks royally. Fortunately the current GF understands that it takes a fair bit of work at times to 'get happy' and if it doesn't happen she understands the reasons why. The best we have found is to spice things up. Sometimes she might just walk in, throw a porno in and get busy, other times she might get vocal enough in the bedroom that it makes me glad the nearest neighbor is 1/2mi away. Roleplay, dressing up, etc. shaking things up and trying to raise the excitement level is key, and even then it takes a while and is not guaranteed. The first thing to do is talk to her and explain what is going on. (research "male anorgasmia") and show her some of the info. Let her know that it's not her, and then see if it improves over time as the meds finish clearing your system. Try adding some Gingko or Yohimbe, if it doesnt help, then look at the Caber or Amantadine. Hope this info helps... if you need more, friend me and shoot me a PM and I will do/share what I can in having researched this.

I had the same issue 2 wks ago, running test prop & mast prop @ 7.5mg ea eod, was like that for three tries in 2 days, couldnt figure it out wife was tripping. 3rd morning was Back to normal. Never figured it out, but was relieved when things worked out with a happy ending. No issues since, I never got a chance to post about it cause it corrected itself

Try something kinky like hair pulling new positions adding chocolate syrup dirty talk.
Make her tell you she wants to cum.
I know sounds weird ima nympho!:/ so yes it takes me forever also but adding this into the mix
Really spices things up and you'd be surprised how fast you'll go after trying all of these.

This used to happen to me when i would take painkillers a lot but shit normally when I don't hit it for a week i can barly last two seconds haha but this problem happens to the best of us...sometimes a little assurance of your own hand helps but other times you might just have to enjoy the time you had, fake the funk, and move on