I went to my dentist several months ago after experiencing crazy pain on my tooth. After several diagnosis attempts the dentist told me I had lost on of my nerves on my tooth most likely from grinding my teeth at night and performed a root canal. Later it was infected and they performed another root canal...

Anyways, I grind my teeth like crazy and have been wearing a night guard since. The thing is now my jaws really hurt during the day and feel like "cracking" them often. I'm not really sure who to see, should I go see my doctor or dentist? Thanks for the help.

Either go back to the dentist so he can adjust the night guard or find a dentist trained in tmj, FJO or neuromuscular dentistry. A medcial dr will not be able to treat it other than prescribing pain meds.