my black 18 month old has developed some kind of bumps and sores beneath her mouth like a mini mountainrange lol.

she doesnt seem to have even noticed.

One bump has a small sore but the others are just white bumps

Any ideas?

If these are on the underside of her bottom jaw then it's likely that they are healed wounds either from scrapping (even play fights can cause scar tissue) or from scratching herself too heftily.

There are also rows of thicker bristly hairs under their chin which have really quite big follicles, so the skin under the chin is often not flat once the cat has passed puberty.

Does she play with other cats? Could she possibly have fleas? If the sores are round rather than scratch shaped then it could be part of an inflammatory process like a flea allergy.

Every now and then I meet a cat who just enjoys having a good scratch to the point that they open the skin up themselves- my Arthur takes chunks out from near his ears and under his chin, even though he's not got fleas or ear mites. He's had lots of tests but the vets have come to the conclusion that he just enjoys a good scratch and we put antibiotic cream on the sore patches until they're healed.

They have just been treated for fleas and there are 5 cats lol currently two ten week old kittens attacking her lol

As long as its not bothering her I wouldnt worry about it

I'd say that the babies are causing the bumps then- as BMW says, if they aren't bothering her I wouldn't worry about them. If they get obviously sore or bother her then that's a different matter and would warrant a vet looking at them.

Know this sounds daft but would i be ok putting sudocream on sore bit?

Yes, Sudocrem is non-toxic to animals and should soothe and prevent any infection. Only use a tiny dab though- it gets everywhere on the fur and is really sticky to remove!

Ace thanks medusa, i must be mad am now up to 5 cats , 2 mad lhasa apso , a fish and a fire salamander lol

You only qualify as mad when you've got 12 cats and a big dog running about the place, like me (although 8 of the cats are fostered and going to their new homes soon).