Baby's losing patches of hair?

Cassaundra
I know it's perfectly normal for babies to lose hair but my daughter, who had a head full of hair at birth, is losing her hair in patches. She got the typical bald spot on the back of her head from what I can assume is from sleeping on her back at night. I didn't think much of it until she started losing a huge patch of hair right behind her ear on the bottom side of her head. She does sleep on that side most at night. She's starting to lose hair on the opposite side as well in the same spot. She did have a 3 week hospital stay due to salmonella and then eventually dehydration so could it be from stress also? I plan to mention it to her doctor next time we go but I'm curious to see if any other mama's have gone through this? TIA!