5 month old and stomach pain?

It seems about every couple of weeks my 5 month old son will wake up and begin to scream in pain. When I touch his tummy/abdomen, it is very hard and when it seems to come on, the harder he cries. This lasts for about an hour. I find that if I hold him against me and pump his legs, it works/soothes a bit (toward the end). Is this colic or gas? I mean, I get the, "Oh, he's gy" from the nurses at the doc's office because I'm a new mom. But I know it's got to hurt something awful because it's a completely different cry from a "fussy" cry. Does this sound normal? He is formula-fed Enfamil Soy and I have been giving him baby oatmeal with pears (constipation). I just want to make sure I'm doing the right thing!