L did a search on bladder parasites and got not much. If you read a bunch of posts here you will find that there are parasites every where and in many horrible forms. I am 65 and when my mother was diagnosed with gardia or ameobas or something I started searching. As I read the symptoms I knew I had terrible infestations. I used Paraguard from Zahler to start getting rid of the bugs. There is a detox that can make you feel very ill. I have never used rx meds, but have had a lot of progress in my health. Usually all advice here says if you can figure out what you have by what you see in the toilet bowl you can attack that parasite, but there are always more, more, more. L learn a lot by searching on google and it brings up stuff like this https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3405611/
Since you started with bum issues I would consider pin worms. Reeses pin worm med from a drug store or amazon actually kills many parisites.
You can click on my name here and read all my posts. There are not a ton, but I always wrote about the most helpful things I found.