Toprol-XL and stomach trouble

I have been on Toprol XL for 8 years. I began taking it when I was 19 after a "attack" where my heart rate was close to 200 bpm for a couple of hours. I was put on Toprol 50 mg for my SVT. This appeared to help but in the beginning I definitely had a slight difficulty with breathing which was exacerbated by stress. It took me a couple of months to get use to the drug especially since my heart rate didn't necessary adapt to the drug right away. I have been trying for a while to get off the medication without the ablation surgery. My cardiologist(s) never thought I should have the procedure since I was so young. It has been a challenge to get off the medication because my heart rate is so high. I was told that my body is so use to the medication that I need to ween myself off. I went down to 25mg for the last year and just in the last week went off of it completely. While I can feel my heart rate (very rarely) every once and a while, it's not enough to get me to go back on the meds. The one side effect that I have had that my doctors have told me about is stomach trouble. Toprol can weaken the muscles in the esophagus (the flap) and cause pain/burning/nausea. My doctors are not 100% certain that this is what is causing my stomach issues but they feel that my prolonged use of the drug has lead to a weakening of my muscle.