Baby and I have thrush right now but it doesn't look bad. Just one patch in his cheek. He also has what looks like a blister on the inside of each corner of the lip when I inspet. Not the gums but actual inside the lips. He is SO fussy constantly. He doesn't act like he has a cold. And isn't throwing up or having any poopie issues. Can thrush be this painful?? What could be the cause of blisters?