This is from a medical text. Hope it's not too confusing:
SPS is a rare slowly progressive disorder manifested by tightness, stiffness, and rigidity of certain muscles with superimposed painful spasms that may be accompanied by increased sweating and increased blood pressure. Examination may show tight muscles, a slow or careful gait, and hyperactive reflexes. Many patients have diabetes. It is considered an autoimmune disease, and in some cases may be a rare complication of breast or other cancer. In some cases, the blood contains antibodies against glutamic acid decarboxylase, which is involved in the synthesis of the neurotransmitter, GABA. Treatment is with drugs that can increase GABA transmission, such as valium.
A qualified neurologist should be able to check for it.
I wish you the best of luck getting an answer to your suffering.