J.P.
arching back, fussiness and spitup are the 3 biggest indicators.
suggestions to try would be:
laying him with his head elevated after eating. You can do this by getting a crib wedge or putting him into a swing or his carseat.
I nursed my twins and I noticed within 2 days of taking silica 6x (homeopathic remedy) that their symptoms got better, better with the silica than with zantac.
I did not try cutting out dairy.
Also, buy the book: The happiest baby on the block. It will help.