I had a similar experience as an undergraduate. In my penultimate year I was struggling under a huge lecture and lab workload, working at the weekends, and par

I had a similar experience as an undergraduate. In my penultimate year I was struggling under a huge lecture and lab workload, working at the weekends, and partying too. I developed stomach pain and went to the campus doctor, who sent me off to A&E (ER) with suspected appendicitis. My appendix was fine, but the doctors thought I might have a stomach ulcer. I discharged myself early to get back to the library, so never actually got a diagnosis! I was drinking 3-4 cups of coffee and ~500mL knock-off Red Bull a day, eating a poor diet, and then drinking alcohol in the evenings. I went cold turkey and spent an entire weekend in bed with the worst headache imaginable. I think I managed a few months before cracking and getting back on coffee. I quit cold turkey again a couple of times but in recent years I titrated off of it by gradually changing ratio of caffeinated to decaffeinated beans in my coffee at home. I drink 1 - 2 small cups a day now. Might give quitting a go again.