10.5 year old Boston is becoming mean

by Lynne
(Rochester, NY)

I have a 10.5 year old Boston....Sully he is a wonderful dog most of the time.....lately, for no reason he started nipping.... sometimes he gets very mean.....wants to bite for no reason........he has a lot of lumps all over his body, the vet said they were just fatty tissue, but I am wondering if there is something else he could be missing....a few of them seem to hurt if I touch them.