My Dr Told Me To Stop Taking Atenol. I Have

My Dr told me to stop taking Atenol. I have been on it for many years. I began to wean off of it a couple of weeks ago, and am down to 1/2 pill every other day. On the days I don't take it, my heart races and I feel very uncomfortable. I will make an app with my Dr to discuss this but I am experiencing anxiety in the meantime. Do I have a right to be concerned?