We just had 5 tumors removed almost 1 1/2 years ago. They just started to appear quickly. This is normal. The vet said that if you play with the tumor and it moves around the skin- usually a good sign that it's just fatty. However if a tumor seems to be seeded like a tree trunk and doesn't move around- then you could possibly have cancer cells.
pycnogenol works from local health food stores.
I don't know if there is anything you can do? I think it's just a condition dog's get when they age. My 5 yr old boxer is starting to get them on her hip area, but she is also 5 pounds over weight and they look like they are going down as she is shedding the weight. Have you asked the vet? What about your dog's weight? Is he overweight?