question: I get a weak feeling in the muscles of my neck begins in the middle then goes out across top of my shoulders and then if i do not sit or lay down it goes down my back feels like its hard to hold my head up. I am on a water pill with blood preasure . I have had lyme desease not sure if its gone haven t been on meds. I know i have been low on magnisium and potassium. Could a lack of either of those cause this muscle weakness in my shoulders. It has also effected the muscles in my neck and tounge when i chew. Feels like they are getting tight and ache.