Oversupply? Help

My little is almost 4 days old, when she feeds lately she chokes. She’ll unlatch just to swallow and cough it out, leaving milk running down her cheeks. When she does this, my boob leaks the whole time, drenching her, drenching myself and the pillows. Also noticed whichever boob she’s not on, will start “leaking” as well if I don’t have it covered with some pressure. Not sure if I should call it leaking, because it comes out as if I were expressing. She also recently started gulping and then gets fussy, and will unlatch and cry. She mostly only does this with one boob. 😥 How do I fix this ?