No Dr's do not answer here, you have to go to the expert forum and pay to post a question.
My answer is to see your Dr...this does not sound STD related from anal sex 2 years ago. But STD's like gonorrhea and chlymida are localized so a urine or swab test would not pick up an infection, you would have to have an anal swab for that to be done. But again see a Dr.
Do doctors answer these questions?