Hi i am Dr Ahmed Aly thanks for using healthcaremagic site , I had gone through your question and understand your concerns .. I dont think your medication is the reason for your back and shoulder pain. i think it is a kind of muscular spasm due to overusing , heavy lifting , bad sitting and sleeping postures . For now i may recommend painkiller like advil tab when needed , hot massages with topical gels , muscle relaxants and some B12 vitamin supplementation will be effective also physiotherapy and even yoga are very helpful . If pain persists i suggest some lab investigations , X rays and MRI and visit your physician Please click THANK YOU and consider a 5 star rating with some positive feedback if the information was helpful. Hope the above information helps you, Any further clarifications feel free to ask.