I have recently started a new med, Tegretol which I take 150 MG per day. I have been on this new med for almost 1 month. I am also arthritic and take Methotrexate,Enbril, and Celebrex. The Dr checked and advised there should be no drug interactions. I don't know what is causing this sudden weakness in my legs. I can 'work' through it but, being 74, it's getting tougher. I will be seeing my internist in a day or so and will discuss with him but I was hoping someone might have some suggestions.