Desk rack bird

Sebaceous Cyst ? - sebaceous cyst condition_symptoms

I recently noticed a knot bubble gum ball the size of my dog in the upper left and moved like a atheroma is not red or shows other signs of infection. Does anyone have any experience with these standards, and what should I do? She is 4 years old Silky Terrier and had a size of a pea about a year back, he disappeared. It seems the cause of the problems to feel comfortable.