I have a pain in the bladder and i think that pelvic muscles cause the pain. how can i check by own if musles work?

Not likely pelvic muscles. I would spend the drachmas and go to uptodate.com and read all about bladder pain and spasms of bladder and muscles. You body is talking to you. Please listen and take good notes. Then share with your Dr. The two of you should be able to decide what the problem is or what is the next step to find out. Once the cause if found treatment is usually easy.