Sleeping, eating and straining

A question for anyone who can help: my baby strains all the time. He is always what seems to be pushing and this is keeping him from really getting some good deep sleep to sleep at all. Also, since he is doing this all the time he ends up spitting up a lot of his feeding. He had surgery for pyloric stenosis already so I know that is not it. I am just worried that this is. It normal. Anyone else has had this problem?