Pain and swelling in my right knee it hurts really bad after sittting for s long time it hurts to straighten it out i've never had this kind of pain before and it seems like fluid is around the knee cap what should ido?

Can be gout.: This sounds like gout, especially since it occurs after sitting for a long time and hurts severely with movement. This usually is first evident in the great toe/right great toe, and then is seen in other joints, and is due to high uric acid. See your doctor to get medications that can stop this now, as well as blood work for uric acid, etc., then go back for treatment plan and diet/med. Rx.

Get examined: This could be arthritis, bursitis or other knee issues which your doctor could diagnose with an exam and possibly testing. Meanwhile, ice and rest may help.