Regular pimples won't have pus in them. Definitely you need a 2nd opinion on this. It sounds like it's been going on for awhile now so you need to be seen by someone else sooner rather than later and get a better work up done and treatment.
grace
Okay you indicated you have been tested for STDs but didn't say the results... I'm going to assume they were all normal. sooo, your doctor is probably right but they could also be folliculitis. Do they occur when you shave??
If you are truely concerned I suggest see a dermatologist.