It has to be your decision of course but if you get to the point of thinking that he is suffering you may want to consider euthanasia but this is entirely up to you. I do not know what to tell you at this point to try to relieve him of his problem. This is beyond my abilities I am afraid. I am trying to get ahold of my friend who is a vet but I am afraid he would recommend that he could not do much either at the distance he is from you.

It does look like a tumor or the only other thing I can think of that could possibly be causing this is internal parasites. I would recommend perhaps trying to treat him for them but it may kill him as the meds for that are sometimes quite harsh.

Rose