56 year old male had a anal fistula a little over a year ago and his left butt cheek get red and veiny looking. He also has pain in the lower cheek that sometime spreads around to the front. He has seen a doctor several times but they see nothing wrong. They just keep prescribing him antibiotics. I am wanting to know what might cause this and is it possibly related to the fistula? Thank you for any help you can give.