On my plecos uhh head I guess, close to his top lip area there is a bubble, almost looks like a brownish snot bubble. I didn't notice it if it was there yesterday, but when I looked today it was pretty obvious. I took a picture, but cannot seem to upload it, as I do not have a computer, only my Android phone, and the upload links don't seem to work. He's just a normal black and brownish lil dude. What could cause such a bubble (or blister?) To form?