Hello,
Welcome to HCM.
This terrible headache with in relation to
sinus infection could be a
tension headache if thinking other than clostridium infection.
Tension headache is a primary or simple headache caused by some precipitating or triggering factor which is relieved by OTC analgesics
(ibuprofen,naproxen,diclofenac) and eliminating this triggering factor.
Tension headache may last for few hours to some days depending on triggering or precipitating factor like heavy sunlight exposure,
sleep deprivation,wrong or uncomfortable posture,eye strains,stress,long working hours in one position etc.
There is no need for MRSA testing at right now,so you can hold unless it is required.
Take OTC analgesic which suits you and take bed rest or sleep with
muscle relaxant and antacid if gas trouble.Try to avoid contact with triggering factor (here sunlight exposure).
If it is not relieved in-spite of taking treatment then you can see
neurologist and undergo clinical examination, routine blood investigations,electroencephalogram or CT brain but only after neurologist advise.
Regards,