While many people dont know this, but smokeless tobacco is just as harmful as smoking
it. It can lead to :-
-Cancer of the mouth
-Decay of exposed tooth roots
-Pulling away of the gums from the teeth
-White patches or red sores in the mouth that can turn to cancer
The increase heart rate
that you're going through is probably an effect of withdrawal from tobacco. I recommend you see a doctor for a routine check up, just to see if the tobacco hasnt caused any problems in your system, after all 5 years is a long time.
I hope this was helpful and that I managed to answer your question.