I am 23 years old. 5' 9" and 206 pounds. In the past week I have quit smoking and am using chewing tobacco only when cravings are real bad. I also have started going back to the gym on a regular basis. I went 6 days out of my first week. Today I went to go for a run and my tongue became like tingly and numb to the point where it was unbearable. It was kind of like my mouth was letting some sort of acidic stuff out in my mouth or something. I had a lot of liquid in my mouth when it does that. Anyway for about 10-15 minutes after I quit running my tongue still felt this way. This is not the first time it's happened but it's really a pain in the when I'm trying to get in shape and got to deal with that on top of it. Any ideas on what it might be?

Yes, this is the result of using chewing tobacco. It contains quite a whollop of nicotine and you are not used to this. To quit smoking and then taking up this other habit is like jumping out of the frying pan into the fire. Stop using the chewing tobacco altogether or you will be shortly hooked on this stuff. If you continue to chew it you will experience all sorts of fun gastric disturbances including vomiting as you will be literally ingesting this tobacco juice in your stomach. Try the patch instead so you don't get hooked. You can get mouth cancer, tongue cancer, throat cancer, esophagus cancer and stomach cancer from chewing this stuff. BTW tobacco juice makes for a great insect killer to be sprayed on plants. Think about that the next time you take a pinch and put it in your mouth. Do you really want to be a "dead ant/bug"?