This heat will kick their butts
I put frozen water bottle/coke bottles without labels, inside their cages, we also have 2 outdoor rated box fans mounted to keep air moving. I've noticed they take a toll on a 80 degree and up day. Pregnancy will make that a bit harder to deal with. Is check the buck's legs and make sure they're sitting correctly also but you probably already checked when you noticed...sorry I can't be more help.
hope she has a big litter shortly! I have one doe that waits til she's IN labor to pull fur and each time I think she's faking me out lol but she delivers 8-10 each time, I would pull mine out, give them my lap and some love and try to feel because I'd be nervous she was preggers and wasn't birthing if I was sure of my breed date definitely.