I got mono a little over 4 years ago now and have had severe acne ever since. is there a possible correlation? does mono mess up hormonal balance?

It's moot: There's no understanding why some people get acne and others don't, beyond that it's sometimes a marker for hormonal disturbances in women. If you've got severe acne, it's your right to have it treated effectively. I'm going to assume that you are using topical benzoyl peroxide as tolerated and that you are not clear. Make an appointment with your personal physician now. Best wishes.