Rolling baby at night

My baby is 16 weeks and she rolls both ways. The past 2 nights she’s been rolling at night. I randomly will check on her when I get up to pump or use the bathroom. When I checked on her she had rolled to her belly and had her face down in the mattress. I freaked out and quickly rolled her over. The rest of the night I stayed up and held her because I was so worried she would do it again. Tonight I put her to bed and went down stairs to relax and checked the camera and yet again she had her face completely down in the mattress. I’m so worried she won’t be able to breath or this could cause SIDS . I work full time and have a toddler so I can’t keep not sleeping at night but I’m also so worried. How do I keep her from rolling ?!