Hi. I've Been Smoking Cigarettes For Almost 4 Years And

Hi. I've been smoking cigarettes for almost 4 years and I know I shouldn't smoke. But the last few days whenever I smoke a cigarette the top of my tongue and the roof of my mouth feels numb. And my lips do as well. I'm concerned about this but I don't have the money to go to the hospital with it and I don't want to go if it's not necessary. What could be the reason that this is happening all of a sudden?