The past few months now my urethra has been very swollen and red and burns when i pee when a urinary tract infection came back negative. what's wrong?

Need std tests: Your symptoms resemble that of " urethritis" . When standard urine tests( urinalysis culture " are negative, you need further specialized tests especially for " chlamydia". This organism is notorious in causing symptoms like yours.If your symptoms persists you may visit a center for std in your area, they can do an extensive panel of test ( free) if there was sexual contact.