Could also be an electrolyte problem, as that seems to be the problem with medication and without. Often it's a lack of magnesium or potassium in the diet. Just a thought.
Are you on medication for the anxiety? Because they often have a side effect of muscle problems.
hi adelle. idk too much about anxiety as far as weak muscles go but I do know that along with emotional symptoms, anxiety can bring about physical symptoms as well. when my anxiety first hit, I did feel very tired and lethargic. I guess you could say weak but I also wasn't eating right so that coulda been a contributing factor as well. has your diet changed at all? hope you feel better soon.
-lynnsee <3