GBS usually starts from distal and then progress proximally. polio is a very rare condition now a days but still possible. proximal muscle myopathy could be because of many reasons. get his vitamin D . ask for any steroid intake. what is the condition in these 10 days. is it improving, same or deteriorating?
Need much explanation of the weakness- eg proximal vs distal, gait, co-ordination and ataxia, Romberg sign, Gower sign , disability score , climbing stairs, walking tip-toe, pain etc. You said pain?? where exactly is it. Is he limping with pain? Anton's gait? Is it hip problem ? inflammatory markers. Doesn't give a clue of LMN or even UMN if pain is jeopardizing his disability and to rule out joint problems or bones.