Hang in there. Allergies can be tamed with all kinds of wierd therapies if your immune system gets out of whack.
You may want to look into something like helminth therapy if you suspect immune system response is causing you illness.
They opened up your distal vas but what about a redo of the proximal vas? Did they remove the sutures up there? If they did not then you are only half way done. Think about it. If that part is still cauterized and closed with sutures then that is likely where your irritation is coming from and I suspect that's where your inflammation has always been coming from. Have a doc go in and resect the proximal vasal ends and reclose them with dissolvable sutures. That might fix your discomfort.
How on earth could anything done on the distal vas affect your prostate? There is a huge air gap there. When they do an open ended conversion they probably don't even mess with the proximal vas (cut end closest to your prostate). Having your own sperm flowing again might shut down the pain too.
My prostate issues vanished almost immediately as soon as I got a reversal.
Your problem will be finding a surgeon that will do it. I would do that before suicide if I was you.