Need help

So last night my 2 month old started not wanting to sleep on her back. She started acting like she was uncomfortable on her back and then it’s like her drool collects in the back of her throat and then goes down the wrong way and it makes her choke a little bit but she does that when she’s sitting up again. I know she’s supposed to be on her back but if she absolutely refuses to sleep on her back and the only time she gets any rest is on her stomach what am I supposed to do??