chlamydia infection
"After taking two 500mg tablets to treat my STI, about 20 minutes after taking I became very very nauseated. Couldn’t sleep, couldn’t lie down. 
After having quite the bowel movement, I remained nauseous for another 30 mins. 
Skip ahead another few bouts of diarrhea and the nausea has subsided about two hours after initially taking. 
Although it does it’s job, it will - even on a full stomach as suggested - make you feel like you wanna hurl. 
But, if I wasn’t willing to go through this, I shouldn’t have had irresponsible sex. 
To each their own."