I had Muscle spasms when I 1st started Mestinon and that is one of the side effects. I still get them once in awhile. I have a slightly high Calcium count and slightly low Vitamin D deficiency due to taking adiuretic in my high BP medicine. The doctors tell me to increase my Vitamin D supplement to lower my Calicum but that just causes more muscle spasms so I just take Calcium by itself when I get the spasm and that seems to work. If it is caused by the mestinon it should subside as your body gets used to it.