Scrotal us revels no varicoceles& no pther abnormalities. after peeing my right spermatic vein swells and hurt. burning and heavy feeling in scrotum?

Hematuria: Blood in uring always needs work up. See your doctor to discuss. Is blood present in your ejaculate? This is usually a benign condition, but should be evaluated as well.

Other possibilities: There are other things in your scrotum that can feel like a vein and which can burn, swell, hurt, and create a heavy feeling after urinating. I would recommend that you see a urologist if you haven't done so already, and if you have, follow up with them.