What Causes Heart Palpitations And Pounding?

I started having palpitations and pounding 2 weeks ago. Found out I have kidney infection. I do not have a fever. I m on antibiotics - dr just started me on atenolol for pounding and palpitations that were coming and going. I still get so cold and feel like heart is trying to pound at times. When I check pressure it s 160/100 When I m cold I m not hungry or thirsty. Eating and drinking put a strain on my system. When I warm up in bed I feel like everything starts working again. What is this. I m going crazy with it.