You are looking for chemical solution to mechanical problem. See you can have mechanical solution to a mechanical problem. The shoulder must have got frozen bcoz of adhesive capsulitis, in which the capsule of the joint gets adhered to the bone leads to decrease movement. There are many invasive and noninvasive modalities available for frozen shoulder. At this platform you can't have second opinion as we can examine the patient.
Next Steps
Follow the advice or get second opinion from another doctor