K.C.
Make sure your baby is latched well - he may be sucking in air when nursing. You should be able to see his tongue over his bottom lip when he is nursing. If you here a "click-click" sound, he isn't latched right and is sucking in air.
Make sure you also know his hunger cues - crying is a late stage hunger cue and babies who get to upset before the nurse sometimes gulp air and get frantic at the breast. These babies often put their tongue to the roof of their mouth, which prevents them from nursing well. Again, look for that little tongue peeking out under your nipple area. Nurse him as soon as he shows the turning head / rooting behavior.
You can tell a baby that is nursing well but the suck-swallow rhythm. Babies will initially suck vigorously, a 3 to 4 sucks to 1 swallow ratio. As the milk starts to flow and the hind-milk starts to come down, they will start to suck slower and deeper. You will see them slow to a 1 deep suck to 1 good swallow ratio.
You also should not switch the baby until he comes off the breast on his own. Babies who are switched between breast too quickly can get a fore-milk / hind-milk imbalance (basically they are not being given a chance to drink the fattier hind-milk and are just getting the fore-milk). This can make a baby very very gassy and fussy.
If you need anything, feel free to contact me.
Peace-Love-Boobies!