Small bumps on cats stomach ?

My cat who is a 1 1/2 year old male has been feeling sick lately. He
has thrown up a couple of times and has hardly touched his food and
water. Today he seemed a little better and when I started rubbing his
stomach I found a couple of little bumps. The bumps look pretty close
to a human whitehead. They don't seem to hurt him since I picked at
one to see if it was just something stuck in the fur. Any ideas what
this could be. I'm worried that this may tie in with his last few days
of sickness. From what I can see there are only two of them and they
look like pimples raised above the skin. Any thoughts before I take
him to the vet on Monday ? He is an indoor cat 90% of the time and
looks fine other than the lack of energy and the bumps.

Rob