intolerance or Illness? HELP

My son is 7 months old, and last week he got his 6 month shot done. He was a little fussy but nothing out of the norm, but when we tried a new form of food, he threw up. I thought it was because he just didn't like it, or something to do with the shots so I monitored him all night to make sure he was fine. Well since then, my son has done a lot of gagging in his sleep (scares the hell out of me), he's been extra fussy, doesn't sleep at all now (up every hour all night) and is still puking up things every now and then. We still give him his formula (no change there), and his cereal. We tried some blueberry purée and sweet potato purée today which he ate well. But tonight he won't go down, he's extremely fussy, gagging again and won't take anything to help him. Normally he's a really happy boy but now idk what to do! Is this something that he is not able to tolerate or should I call his doctor??