Withdrawal symptoms

Hi, I have successfully quit smoking three months ago and I chose to go cold-turkey. Since then I am having mouth ulcers (on and off), and sore throat very often. I still dunno why it keep appearing.

After quitting smoking I exercise regularly, take healthy diet, avoid coffees to avoid smoking. These habits helped me to convince myself that I am switching from unhealthy lifestyle to a healthy lifestyle.

I have been a heavy smoker for more than 20 years! Almost a pack a day!