What Causes Pain In Leg?

I am 65 years old and am 5'9" and have been battling Evans Syndrome (similar to ITP)for 12 years
I had a brain bleed in January 2011 and had surgery to fix. Got over that quite well. It has been 5 months now and my legs get so tired and weak and ache in the thigh bone. I also have hypothroidism which tests result every 2 months are up and down.
Can you tell me the cause of my leg pain. Could it be varicose veins for I have the beginnings of them too.

Thanks