@dianel44
Mostly likely not osteopenia causing your fatigue or pain.
A few things to consider:
Shoulder pain: You may have a rotator cuff problem. I have a torn labrum in mine. I cannot reach comfortably with that arm nor sleep on it. You need to have the shoulder checked by a good orthopedist. An MRI might better tell what is going on with it. An injection could help with inflammation.
Fatigue: are you sleeping less because of pain? Are you eating well? Are you exercising enough.
I have bad feet .. bone on bone arthritis and the surgery to fix would be a hard recovery .. and cannot walk long at one time. I bought a cheap fitness tracker (Proyoo brand ..I replaced the silicone band with a mesh one for comfort .. bought both on Amazon). There are many other brands out there in same price range. Most fitness trackers are not very accurate on sleep and blood pressure measurements. More expensive is not necessarily better. They can help you set a goal of how many step you take in a day and track other exercises. Most days I get 4000 steps instead of my goal of 8000. I have had the tracker for a couple of months. I have got to work harder .. but fighting sacroiliac pain too. Hopefully will get an injection soon.
Vitamins and hormones: Have you had them checked? If you are taking high doses of Calcium and Vitamin D they can make you feel fatigued and hurt all over. Low Vitamin D, Iron, B-12 and Magnesium can make you tired. Have your Thyroid checked too.
Medications: Some medications can also make you feel tired. Go over your medications (including over the counter medications) with a pharmacist. .. believe me better than talking with your doctor. The pharmacist can give you information of concerns about you medications to talk with your doctor or they can talk with the doctor about them for you. A statin caused me pain.
I am one that has the odd-ball reactions to medications. I tried Prolia .. one injection. Within two hours I felt like I had a stomach ulcer. Nothing I have tried with medication has helped my bone density number .. so I am doing my best with food and vitamins. The medications have helped many with no side effects. So don't be discouraged.
When you have pain what will make it worse is inactivity. I use my arm despite the shoulder pain. I don't lift anything heavy with it and I do not strain to lift with it. You will know your limit of movement. I did physical therapy that helped me find my limit with with my shoulder and exercises to do. … with my sacroiliac too. It is holding me back on my walking more than my feet. I use a TENS Unit to help with both of those areas when the pain intensifies. .. usually when a low pressure weather front comes through. I think my husband paid less that $50 for the TENS Unit and extra electrodes.
Sorry for the too long post .. maybe something in it will help you.
ZeeGee
I have shoulder pain too. I'm 71 and was raising my arms above my head to cute back a hedge and that did it. It's a month now and it is slowly getting better. However, as you said, I can't sleep on my side but I did find that putting a small pillow under the damaged shoulder makes sleeping a bit easier...good Luck !