I was put on Diovan and was okay in the beginning. But then I not...

I was put on Diovan and was okay in the beginning. But then I noticed when I would just get up and walk around my heart would race. The other night I took my blood pressure which was fine, but I knew my heart was racing, it was 105 beats per minute, I felt exhausted, and worn out and plain tired. I need to be on a Beta Blocker so I went back on my Atenolol. I also would be out, if I turned to quickly, my head would take a spin and I would have to grab something to keep from falling down. I'm one of those people out there if there is a side effect to have it will be me. D.S.S.