Bleeding while on Loestrin Fe 1/20

I am taking Loestrin Fe 1/20 for endometriosis. I have taken Loestrin Fe 1/20 before and have had much success. However, now that I've resumed taking Loestrin I have been bleeding continuously for the past two weeks. Just when the bleeding seems to slow down to a tricle, I experience cramping and regular bleeding ensues. Is this considered breakthrough bleeding? If so, how long can I expect for this to occur?

Thank you,

Toni Lee Acevedo