I don't think it's the food...sounds like he eats pretty well. It may be a nap issue. If you don't think it's his nap then it may simply be a case of wanting mommy and daddy.
The trick I used was going into the room but not picking up my daughter. Usually the simple knowledge that I was there would calm her down until she went back to sleep. Sometimes I would rub her back or sing a song or read a book if she looked as though sleeping was the last thing on her mind.
I would deffinately stop changing and feeding him both times he wakes up. He will form a habbit and expect it from you every night. If he's not too wet I would leave the diaper alone. You could try feeding him some extra formula before bed perhaps a little cereal as well. The warm meal may help relax him and help him sleep better.
Our routine used to be, bath, bottle, crib and book with low lights, goodnight.
I wouldn't fret too much though. It's common at this age for children to develop a bit of seperation anxiety.
Hope he starts sleeping soon!