It turns out the "tumor" was his testicles He wasn't neutered and that's why he was "peeing" (marking) so much and I'm not sure if it was blood or just dark from being dehydrated. I guess his general condition can be explained by him being loose for 3 days (except his stained teeth). We have a pretty good humane society so I have to believe they looked him over and felt he was ok. I'm going to go there this weekend and snoop around and see what else I can find out