What Causes Lower Abdominal Pain And Burning Sensation In Throat After Starting Toprol?

I have been taking Toprol xl for 2 months after an episode of afib. I previously took propranolol 80 daily for 20 years to control heart rate but after episode of rapid afib I was changed to toprol 25mg twice daily but reduced it to 12.5mg twice a day due to bp bring low. For 3 weeks I have had lower abd pains, burning on throat and bloating - it seems to occur after taking toprol. Could this be a side effect?