I've tested NEGATIVE, what could it be now?

Recently I was convinced I had an anel STI, so I got tested and surprisingly, the results where negative. I got tested because for MONTHS, around the hole of my anus would itch and there was a discharge and smell********. She gave me an antibiotic on the same day I was tested because she thought I had chlamydia from what she saw . However when I got results, everything I was tested for was negative??!!. So im still stuck with this itching, smell, and what I think is a discharge. I must say , I do get hemorrhoids, and She did not test me for trihomoniasis, could it be either of those.?