im on birth control but...

my doctor prescribed me with birth control pills about a week ago and now she recently prescribed me with pills that will help my BV go away and I went to pick it up today but I don’t know if it’s safe to use two different kinds of medicine in my body at the same time. do I finish my first month of birth control first and then start taking my treatment pills? or?? Also I think dropped 4 tablets on the ground because I was counting them and all I found was 3 and I was looking everywhere for it but then I started to think they probably miscounted :/ I don’t know.