My legs are very tender to the touch. uh, they only hurt in the back. hard to walk/ stand on. gets better with rest.

Varicose veins?: You may have venous insufficiency -- your primary doctor should examine you, and make a recommendation, but you may want to start with compression stocking therapy.

Sounds like: Muscle pain, especially if it is both legs equally. Or it could be thrombophlebitis, which could cause pulmonary embolism, a potentially deadly condition. Get this one checked out. It could be medication side effect, or pinched nerve in lumbar spine.