Tummy sleeper with swollen eyes

So my 7 month old has been sleeping in her crib for about a month now and sleeps on her tummy. About half the time she wakes up with one or both eyes super swollen! I took her to her pediatrician and she was a little stumped. She thought maybe an allergic reaction to detergent so I washed her sheets without detergent and dried without a dryer sheet. There hasn't been any change since then! Has anyone else experienced this with their babes or know what it might be from?!