Headache every hour 😞 37 weeks pregnant.

I have a headache for almost 3 days which is so mild and it comes and goes.Everytime I wake up in the middle of the night I get a headache after a nap or even just in general.I took tylenol and the headache comes back after an hr or so.I have an appointment in 2 days I will mention it to my midwife.Ive been drinking water thinking it's maybe just dehydration but the headace won't stop.Its so mild but it's annoying.