Might be hand foot and mouth disease adults can get it too. Is he in pain?
Yep, my little girl and husband and I have also had bouts of this. More than likely hand, foot and mouth as you can get it more than once. Only my husband got the hand and foot ulcers, my little girl and I only had mouth ulcers! It’s everywhere at the moment!!
If it is mouth ulcers try using a different toothpaste as its a well known cause of mouth ulcers
How old is your little one? I noticed one in my little one’s mouth this morning x