pill switch weird discharge

So I've been on bc for almost 3 years now but in the last two months the pharmacy has changed my brand twice. They say it's the same because the active ingredients haven't changed but I've been having all sorts of weird reactions to the different brands, like migraines and joint pain. But most recently it's been brown stringy discharge, my period is only a few days away but I've been having the discharge for a few days now. Wondering if anyone else has had something similar happen?