bacterial infection
"I seem to be the only one who reacted to this stuff with noticeable chest soreness- not really cramps and thank goodness no vomiting, but my chest feels all sore. And, especially at night, I also feel rather out of breath. 

The prescription was for a rather severe infection from a root canal. Said infection made my entire upper lip swell up completely, was so painful and sensitive that I was popping Ibuprofen along with Tylenol every six hours, every day, for several days. Clindamycin probably had some effect, but what really made a difference was a specialist physically draining the infection. Otherwise it wasn't going down."