I just had hairline lowering surgery. My hair is falling out, leaving bald patches and an exposed scar

Hair loss following a hairline lowering procedure, like any facial plastic surgery is a known risk. Many times, in men who get a hairline advancement surgery, it does not come back. If you lost hair at the advancement edge, the scar will have to be covered with a hair transplant. Usually women lose hair in the corners of their hairline and this is almost always permanent so a hair transplant will also address this as well. Hair loss elsewhere may reflect a dermatologic problem which should be diagnosed if you have one. The diseases such as FFA, LLP and other types of scarring alopecias need to be ruled out in the evaluation of your problem