Hi i am Dr Ahmed Aly thanks for using healthcaremagic site , I had gone through your question and understand your concerns .. In my opinion the pain of your upper thigh is kind of a muscular spasm from your normal daily activities as an aqua areobic teacher with age above 80 years and very active is actually very normal and may be releived by icing it post excersizes and topical massaging by muscle relaxants containing gels will be effective but i think your numbness is either from a nerve injury or compression like sciatica or a vascular underlying disease like a minor clot or low vascularity to your left foot . For my patients i may recommend some lab investigations and Dopller U/S on both lower limbs to compare vascularity . elevation of legs , wearing ankle support , antiedematous drugs from OTC for now till results of your examinations comes . 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.