Hello Nex,
There could be many causes for this kind of condition to develop and only a vet can diagnose the condition after examination and tests.
There is a comprehensive list of caues of lumps which may develop on a cat, some which are easy to treat and others which are more serious.
To read this list, please go to::
Causes of Solid-Appearing Lumps & Bumps on the Skin in Cats
Don't get too alarmed until you know what the cause of these lumps are, but get her to a vet as soon as possible.
The quicker the condition is diagnosed the sooner treatment can start.
Good luck and good health to your cat.
Please let us know the results.
Thanks.
Cy
(Poseidon)