G.S.
This might be a long shot but see if he needs his frenulum clipped. It is the skin under his tongue....I went to a lactation consultant.(usually the hospital has one) at no cost and she said that it might help him latch on and maybe even help with his spitting up. That didn't get better until 6 mo when he started sitting up but the frenulum being clipped did help he is 1 yr and I am still nusing. The diagnosis was actually called tongue tied. My husband and I both have extremely short tongues. It is worth looking into......Good Luck
G.