The parathyroids have no relationship to the
thyroid gland, except for the location in the body. Throat pain when swallowing and the night sweats and the leg pain could indicate a thyroid condition. Where is the pain when he eats spicy foods? That could be a gall bladder issue.
The tests he needs to check thyroid function are TSH, Free T3, Free T4 and thyroid antibodies, Thyroid Peroxidase Antibodies (TPOab) and Thyroglobulin Antibodies (TGab).