I got back from holiday on Oct 11th and started back on my fast days which took place on the 13th, 15th and 17th.
The first two were perfectly normal however the 3rd day I woke up after an hour or so with a blinding headache and did not sleep at all. Think I might be just coming down with something. I had the headache before going to bed but not nearly as bed.
I guess fast days can be that bit harder if your system is a little run down. I still have the headache now plus a sore throat so hopefully its something that will pass quickly.