Help, what could this be? Babys mouth swollen?

So my almost 5 month old was chewing a toy and I noticed what looked like a swollen bubble in her mouth. So I kept trying to look and it's like swollen on both inner cheeks as if she was chewing on her cheeks (no teeth). So I tried to get some pictures of it... tried googling online and it says "mumps" eeeek... my older kids go to school then home and around my baby so could it be?.... I tend to talk her in the doctors when they open....

Besides this swelling and fighting sleep she screams some time as if she's in pain I thought maybe teething but I dont see any swelling yet or feel any hardness.