You have let it go on for a few months? This is a painful condition, I had problems with my prostate and suffered similar problems with urinary retention, you need to seek medical attention.
Don't accept it when they say there's nothing they can do, there are other anti-inflammatory and medication you haven't tried, if infection is the route of this (which is highly possible) then you need to be on anti-biotic urgently.
Infection causes acute inflammation and oedema of the
bladder mucosa.
Another treatment is to have a catheter introduced, this will help you relieve yourself at least - although the pain will still be an issue.
Doctors and insurance companies have quotas, but don't let them tell you a condition like this can't be resolved because it 100% can and I am living proof of this