Have you been diagnosed? What meds are you on? Weakness can come from meds or it can be a symptom of lupus, myositis, or an overlapping connective tissue disease. Of course, there are others than can cause weakness but I am only listing some from the AI family of diseases.
I have mctd which is lupus, scleroderma and polymyositis. PM hit me like a freight train and I lost 40 lbs of muscle mass and was a quadriplegic only 15 months ago. Fully independent today and recovering slowly.
If you have not seen a rheumy you should and list all your symptoms. The earlier you can get a diagnosis and effective treatment the better the outcome. Early diagnosis is not always possible.
Muscle atrophy can happen in a very short time. You can address that by doing mild exercise. Anything you can do will help and light resistance training (weights or weight machines) can help to restore your strength. Yoga or Tai Chi are good all around and gentle regimens that can help cardio, flexibility and strength. Enroll in a class or buy a cd from amazon. I started tai chi over a year ago when I could barely stand. Could only do the basics but it helped. Today I am actually helping disabled people learn tai chi.
If you don't want to tackle yoga or tai chi then just walk and use some light weights. You can also do simple exercises like Hindu squats for lower body and core strength...no equipment needed. Do a google search for instructions....they are easy and address strength, cardio and some flexibility issues.
Mixed connective tissue disease (systemic lupus, scleroderma, polymyositis), Raynauds phenomena, Hypertension, Barrett's syndrome.
Meds: prednisone (9mg & tapering), 150mg imuran, lisinopril 40mg, maxide 37.5/25mg, norvasc 5 mg, folic acid, potassium, aciphex 20mg, multi vitamins.
Maintain your optimism and you can beat the odds.
"Although the world is full of suffering, it is also full of the overcoming of it." Helen Keller