What Causes Pain In Lower Abdomen And Penis Post Masturbation And Urination?

Hi, I'm a 27 year old male. I masturbate 2-3 times a week.
I've been experiencing pain after masturbation and urination in the penis and lower abdomen for a long time (maybe nine years).
And I've got used to it.

However, four days ago, I masturbated while sitting on a very low chair (knees close to chest), and the orgasm was painful and it felt like the fluids where trapped. But I came never the less.
After that the usual penis and lower abdomen pain became very bad. And a lot of the time I feel like my bladder is almost leaking urine.

I tried to masturbate while standing after 3 days but I had an orgasm too soon with no fluids at all.

What's happening and what should I do?