Yes a headache can be a sign of the coronavirus disease.
I recovered from the Coronavirus disease a month ago and yes I did have a headache before the coronavirus disease started getting worse.
I also had diarrhea along with the headache and did have some trouble breathing but not severe enough to go to the emergency room.
If you're overall healthy you should recover from the Coronavirus disease without any issues but if your breathing does get worse then call 911 or get to the emergency room.
But mostly try walking around and only lay down when needed.
The more you move around the better off you're gonna be.