My right jaw bone hurts every time when i open my mouth wide & sometimes i hear it crack. any ideas what's causing this?

One possibility is: Tmj (temperomandibular joint) dysfunction. I would encourage you to see an ear/nose/throat specialist for evaluation.

TMD: It sounds like you have a temporomandibular joint disorder. The symptoms usually involve facial pain, pain with jaw function, limitation of jaw opening, or a cracking or popping sensation with jaw function. Triggers may include teeth grinding, certain sleep positions, or frequent gum chewing. First-line medications include a 10-14 day course of an nsaid, such as naproxen.