Can an armpit boil cause breast pain? it looks like a pimple. and some have black centers. there not very big. i had just one for 5 years

Yes: You may feel pain in your axilla (arm pit) that is refered to your breast. Are there any masses in your breast? If the boils resolve and the pain persists you should see an md. If the boils are not resolving with warm compresses etc you should see an md. Finally, you should be doing self-breast exams once per month and having an md exam every year. Any suspicious masses should b biopsied.

Sebaceous cyst: This sounds like a noncancerous lump called a sebaceous cyst. They can get infected and become painful. I recommend you see a general surgeon or breast surgeon who can evaluate you.