Not sure what to do

So last week I started bleeding. thing is my period is 20 days away. I was bleeding abnormally for a couple of days. between next to nothing to filling up a pad. I went to see an obgyn on Friday. they said it was just an early period or a side effect from the constant switching of brand name to generic bc. they did and internal examination, checked for any tearing or infection. did a vaginal ultra sound because I get cysts that rupture. that came back normal. they even did a culture and it came back ok. The bleeding went away by Monday. Then all of the sudden today in bleeding again and this time really heavy. Not sure if I should just ride it out or go back to the obgyn. thing is, I have endometriosis which can cause problems, but I've never ever had this happen to me. where I supposedly have a period and then only a few days later have another one.