Im sorry to hear about your symptoms.
From what you are describing there can be a number of conditions which can cause this sort of fatigue. The first one which comes to mind is that you could have an underactive thyroid gland. This can cause the extreme fatigue as well as coarse skin, slow reflexes, hair loss as well as constipation and weight gain. A simple thyroid function test would be diagnostic here.
Another cause can be a problem with the adrenal gland which can cause this problem. Again a cortisol level would have to be done as well as as 24 hour urinary cortisol level. This would be corrected with steroid replacement therapy.
Another cause can be associated with autoimmune diseases which can be diagnosed with the help of tests like ESR and ANA followed by a complete ENA profile.
Lastly a vitamin D deficiency can also cause fatigue as well as the pains which you are feeling in your limbs. This can be diagnosed by getting a vitamin D level done.
So i would suggest that you contact your doctor and have these conditions looked into and get the above tests done.
Do you have any more questions?
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