Anyone seen this weird thing on their babies teeth?

[Essecks]

My baby hasn’t been eating today, he’s 13 months old and he’s been fussy. I’ve had a look in his mouth to check for pegs and seen this blister like thing above his right tooth. Anyone seen this before and have any clue what it is?

My boy had something similar after falling and hitting his mouth

Ow lots of teeth coming through there. I had forgotten that stage :). That looks like a nasty mouth ulcer - maybe he banged it or has a virus about to come through?

Just seen how bad the quality is! Adding a close up pic to see if it makes it any clearer

Looks like an ulcer to me.

Are you giving your child any baby vitamins? If it’s an ulcer it may be a low folic acid level

Not sure whether you know, but could this be due to drinking oat milk rather than whole milk? He’s lactose intolerant but I’ve been trying the milk ladder with him off and on. He eats a lot of veg but I’ve given him vitamins the past two days purely cause he’s not been eating and am going to start as we give my 4 yo vitamins daily as he has arfid.