21M, 130lbs, Diagnosed with Hyperthyroidism in June 2018

Essentially since I've been on these meds to help with the side effects of Hyperthyroidism, I cannot leave my bed for roughly an hour after I take my meds (Toprol XL 25mg x2/day, 2.5mg Methimazole, 10 MEQ of Potassium) otherwise my Heart Rate skyrockets into the 100s. This causes me A LOT of anxiety and it seems like it sticks around for the rest of the day once it starts spiking. I understand Anxiety can cause high heart rate (trust me, I am honestly TOO familiar with this), but why is it still so high even though my Thyroid Levels have normalized?