I had anal sex for the first time Sat night/Sun Morning where the penis went from the anus to the vagina. On Monday I began to have a burning feeling down there (constant around labia). I also noticed a bump inside the skin on the labia left side. The bump is hard and feels more like a zit that I would have under my skin on my chin area. The bump does not seem like a sore or blister. My doctor thinks this may be from herpes. I asked my pharmacist and he thinks it is more of a UTI. I took a at home uti test and the leukocytes was positive but the nitrite was negative. I am currently taking doxycycline. First dose was last night so have not felt much of a difference. I am just very stressed out about the possibility that this is an STI since I have been careful with "selecting" my partners (all have claimed they are clean 4 total).