Aww poor Layla! My younger twin sisters' Yorkie, Cujo, gets warts and skin-colored bumps sometimes. We took him to the vet and she said they were Sebaceous Glands, or in this article they are calling it a cyst. Our vet didn't seem too concerned about it, she just stuck a needle in and drained the fluid. The bump was gone within a few days. She said just to bring him back in if he gets anymore, they go away quickly once drained. This article,
Sebaceous Cysts In Dogs And Cats | MyPetsDoctor.com, says surgery is required if they get too infected and opens up. Hope this info helps you out! Good luck to Layla!