Brief Answer:
several possibilities can be there..

Detailed Answer:
Hello XXXX, Welcome to HCM,

I've gone through your query and understand your concern..

Now I believe you're referring excessive sweating over your head,neck and face as the primary concern..

Yes it can be there due to fibromyalgia, but it should not suspected as the primary concern..

You need to get checked for Diabetes (FBS, 2HR PPBS, HbA1C and Urine routine microscopy) in the first place (if you've checked already then please let me know the results) along with hypoglycemia(should be suspected if happening specifically at night)..

Secondly, cardiac check-up must be done along with EKG to rule out any impending anomaly (heart failure etc.), if done already then please let me know about them..

Few electrolytes like Sodium, Potassium, Calcium and Magnesium should also be checked along side as disturbance in these level can cause this too..

If your taking any excessive caffeine/salty/spicy food, please avoid them for the time being and observe how you stay after that..

If everything else's within normal range, then you may held fibromyalgia as the responsible cause for which there's might be need to visit your neurologist for a detailed check-up(which i believe you must've done already)..

Let me know if there's any further queries, I'll be glad to clarify..

Take Care
Kind Regards

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