Amy idea on how to take care of this, or what it is???

Hello there ! So a local stray who is somewhat friendly has been coming around. I recently noticed this issue on his tail...it almost looks like a cat bite to me. It is tender, and is making him irritable. He still eats, drinks water (we leave some out for him) and while he was laying on the towel we set for him outside I was able to get this picture with minimal scratches. I tried to get him in a carrier, but it did not work out well. I was hoping for some advice on how to help this guy out, just in case I cant manage to get him to a vet. I will try again when I see him next, but he ran off after the last attempt to crate him. Any suggestions to take care of this or help him is appreciated. Thank you in advance !  

Oh no - how difficult!  I also think that a cat bite abscess is likely for a swelling on the tail like this, although one can't completely dismiss the possiblity of a tumour from this distance, and one or two other things.   Unfortunately there is a legal issue here - this cat may belong to someone, and the possibility can't be excluded that treatment is already on board.  Furthermore, the cat may be owned and lost.  I have known vets offer to lend a microchip scanner - some apparent strays, perhaps bribed a little, might allow themselves to be scanned if not touched.  Some animal charities have the equipment to trap stray animals in order that they can be examined and scanned.  Perhaps either of these might be a good way forward in this case.