[Ria P]

She's a lovely looking hamster and lucky to be living with you now.
Yes, she needs to be seen by a vet asap.

It sounds like an infection and could be pyometra. A friend's Syrian hamster recently had surgery for pyometra and she's doing very well.

It could be something else like an abcess but whatever it is, it needs professionan help. Your hamster is young enough and looks to be fit so should make a full recovery from whatever ailment she has.

I must say that i've only ever had male Syrians so have no first hand experience with females.