It is likely breakthrough bleeding. A fairly common side effect. You should wait a while before going back. If you are not bleeding very heavy, wait for a month. It will most often just stop after a few weeks. Your doctor can do a few things if it does not stop by itself - stop the pill for a !**@! the dose, change to a different type of pill or give it more time. If you are feeling tired, take an iron supplement until you get to the 4 iron pills at the end of your pack. Don't overdose on iron though.
It sounds like your doctor thinks you have PCOS (ovarian cysts). This will normally highten your androgens (testosterone), and birth control pills is how it is controlled.
Take care!