How can i tell if it's joint pain or pain in muscles, bones, nerves, ligaments and/or tendons, etc, nearby (neck, l shoulder, r knee, etc)?

Hard to tell: Hard to know for sure. Tendons hurt when they try to move against something that wont move, ligaments hurt when stretched or pressed. Bones hurt when they carry a load or when pressed. Muscles hurt when compressed or pressed on or when they are used.Joints hurt when they are moved most of the time.

You can't: you need professional evaluation to determine