Ablation great until....

I am new to your forum and I am learning, Thank you everyone.,I had an ablation 1 year ago, Doc. says it was successful and everything has been great until approx. 5 months ago, my heart rate stays in the 100's, before getting out of bed, I check it, and it reads 100/105 bpm. While resting, the rate can settle around 110. Doc' says exercise, but it shoots into the 135-147 bpm. with shortness of breath, heart racing. I work in kitchen preparing dinner (no straining, little effort) it will move into the 116-125 range. I have learned here, this problem is IST. I have another appointment next week, and now I feel I am better informed plus I will continue searching here and learning. I hope I am on the right track...What will be my next step? Can med's help this ? Oh I am taking daily aspirin and Diltiazem 240 mg. Can anyone help inform me ? Thanks in advance...