Changed BC

So last month my BC changed because the pharmacy I go to no longer carries it so they gave me the equivalent generic..so they said. Ever since I’ve been taking it things have been off, last month my period was a day early. No big deal, I wasn’t worried at all. Now this month it’s a whole 9 days early and I’m annoyed. Has this happened to anyone else? Should I check in with my doctor. I’m not completely sure if this is normal, I feel like it could be since I’ve switched just a side effect of the change but I’m not sure if it’s worth a trip to the doctors.