I had the same thing happen to me - just one foot. Try slightly adjusting your saddle height down, the overextension could be cutting off blood supply. Try loosening up your shoes a bit and make sure your bike is level when in the trainer. If your shoes are super tight across the top of your foot, it can cause hot spots and maybe even "sleepy foot". For what it's worth, since I got custom footbeds for my shoes, all foot pains, and sleeping sensations have gone away.