Help!!!! I need advice

My 5 month old rolls over to her stomach while sleeping and just lays with her face to the mattress how do I get her out of this habit she can’t sleep in her crib because of it and she has severe reflux issues so she has to sleep on her back or she could choke in her sleep.but now with her rolling from her back to her belly she could suffocate on her mattress. I really need advice!!