I have tingling going down both arms and back. Sometimes in the legs. It's worse with activity or at end of day. What could cause this?

Tingling. Tingling usually is the result of nerve compression and is dependent on position or what you do. It can improve on its own, by avoiding the compression. If in both arms and legs, the problem could be in the spine, maybe from a prior injury. Also consider B12 deficiency, diabetes or thyroid disease. Other nerve damage could be the cause as well. If persistent, seek your doctor for work up.