Stinging in tip after urination

i need help desperately I have been dealing with this for 6 months seen so many doctors and a urologist they said everything looks normal had scan on my kidneys, my testicles which were a little swollen at time and thought to been hydrocele , that's the end I heard of that, I also had a camera up the pee hole and everything looked normal I have had antibiotics for uti, also had doxy and the 1 time pill for gonnorhea and chlamydia, had about 4 blood tests and 13 urines 2 swabs all negative but everytime I urinate about 10 minutes later I get a sting, and a mild burning sensation right at the opening of my penis, I have no discharge, no bumps or lessons everything else looks normal apart from a tiny bit of swelling in slit of penis

i find if i stand it relieves pain alot but if I sit down it comes straight back on

Get examined for prostatitis