Also, have you considered food sensitivities? Faolan is sensitive to dairy and the only sign of that we had was gassiness (but farting, not burping), so I figured it was normal for months until I just quit bfing and put him on nutramigen.
Forgot to mention that arching the back is a sign of discomfort in infants.
H&T Mama to Faolan
6/7/12 & Malachy
born into heaven at 14 weeks