Lumps in hamster cheek (not food)

[SabreRose]

I moved my Syrian into a new cage yesterday and gave her food. For the rest of the day she was exploring the cage with full cheeks which I put down to stress and her not having a place to hoard figured out yet. But after a while I was worried about them being impacted.
I saw her this morning and it looked like she'd emptied her cheeks but tonight her left cheek (well it's actually a bit lower than where the food would be) looks big. (The right one is fine) and it feels lumpy. Not like food lumpy. The lumps feel softer. And you can really see that it's swollen or sticking out.

I'm definitely taking her to the vet tomorrow but does anyone know what this is?
could it be impacted?
I'm thinking something a lot worse and am really worried.
Has anyone had anything similar with their hamster.
She's my baby and I hate to thing she might be in pain or really sick.