Help me diagnose this sound

llizzyb

DS has been doing great nursing. The past week, he's started making a clicking/slurping sound when he nurses. It's on both sides, and occurs throughout the feeding. It definitely leads to extra air intake, which is causing him more gas.

I do have a fast let down, but since this occurs throughout nursing sessions, I don't know if that's related. 

Thoughts? Should I see an LC? It wouldn't be an issue except for the extreme gassiness we're dealing with already.