Hello and welcome
Hamsters are pray animals and very adaptive so they hide pain well.
Anything face related really does need a vet visit. Even if it was an abcess that has started to heal, it may have been caused by a dental issue, or could have partly drained. Either way, some anibiotics and a proper examination of the pouch and mouth would be adviseable.
Often small pets are not seen "worth" a vet visit like say a cat or dog, to some family members. However, when we take them on, we owe them the same duty of care as we would any pet..morally and legally. Vets are expensive so having a vet fund is vital when taking on any pet. Exotic vets (who specialise in small pets) are often harder to find also so it's good to research and prepare in advance.
Offering sof foods such as baby food, chicken, soft veg, egg would ease the strain if there is something trying to heal there.
You mention you clean the cage weekly, this shouldn't be needed if substrate is deep enough and can cause stress having the home changed around so often. During clean outs, you should be able to check your hamsters store to see how much they are eating vs storing. When giving wet foods it's important to check these though so nothing goes mouldy.
Good luck, but I really would advise a vet visit sooner than later