Syrian emergency

[MismatchedMongrel]

Hi everyone! I took my oldest ham, Einstein to the vet this morning because last night I didn't see him running on his wheel the last few days (and this is a ham that will go for seven hours a night, consistently). I picked im up and noticed several things:
a. his left eye seemed either swollen or bulgy, the fur is thin around it and its watery.
b. he's got blood in his urine.
He's a half-feral rescue and hes got to be almost three years old.
But anyway, we went to the vet's this morning (I just got back). The vet is a bit suspicious of it. She says with his age it might be cancer.
But he's still eating and getting around okay (still lethargic). I asked if it would be worth giving him a chance, because I didnt' want to push him for no reason or make him suffer.
She said its worth a try so we left with vibramycin and some eye drops.. neopolydex.
Does anyone have any insight into this? He's eating the fruit and veggies out of his food every night so that's what I put in there.
Insight would be great.. I"m really worried about him.