Sticking head in shell, gaping mouth.. please help!

Hi,

My tortoise has begun behaving strangely over the past week. She is still eating fine. But she keeps sticking her head in her shell and covering the hole where her head should be with her front feet. Then she sticks her head out again after a couple of seconds and repeats (can't tell if she's scratching her eyes or maybe straining? Her eyes keep closing). Then she opens her mouth lots and gapes up at us. Usually this is because she's hungry because she knows we bring her food, but we are concerned it's a symptom. It's been very hot recently and she has been eating much more than usual... could it be eggs or a more serious problem? Thank you!!