I've been experiencing a burning sensation in a vein in the area between my thighs, I think it's called the perineum. It started when I walked, and I thought it was because of my pubic hair, so I trimmed them. But then I noticed a thick line from my anus to scrotum, maybe a nerve, that burns whenever it's touched. Now it's really tough for me to walk. What could be causing this, and what should I do?