how shingles may cause a headache

You likely have it in your trigeminal nerve. It’s a VERY painful nerve, and maybe about the worst place you could get it. I would recommend you phone your regular GP soon and see if you can get in. If that’s not an option try a dermatologist

There are drugs that can help with this. One is amitriptyline, which is an old anti-depressant that helps heal your nerves (and this does work). Also the drugs you see advertised for nerve problems with diabetes can be used. The sooner you get treatment the better off you may be here. I would not let this go for several days.