Mystery Weight Loss plus Cranial Pain

I'm wondering if anyone has any light to shed on my mother's mystery ailments. Since October, she has been experiencing very sharp pain in her entire head area, starting in her temple area and going from one side of the head to the other. She describes it as a burning sensation, goose bumps. Excruciating pain, not responsive to over the counter pain medication. It gets worse at night so she is unable to sleep without heavy pain meds. Also, she is experiencing 1-2 pounds of weight loss each week. She's dropped a lot of weight and continues to do so. I'm not sure if these two things are related, but she was recently diagnosed with Hashimotos, which has been left untreated her entire life (she is 64 years of age.)

Does anyone know what is going on with my mother? No one, not even the neurologists can explain her symptoms. Some think it's TMJ, others think its Trijeminal Nerve Disfunction. But no real diagnosis.

She is in excruciating pain and I'm afraid for her life. Any help would be very much appreciated!