New Hyperthyroidism with chemotherapy

There was a thread on this topic several years ago but I thought I’d start a new one
I’ve been admittted to hospital twice in May with tachycardia. I’ve been on treatment for over 4 years and on my current chemo for 18 months. I’m waiting to see an endocrinologist but I’ve been referred to one whose specialism is with diabetes and big one with oncology.
I’ve also been prescribed Propylthiouracil which has tendicies to cause liver damage even death and I have liver mets! I also have a beta blocker to control my heart arrhythmia and don’t see why I need the thyroid drug if my heart is being controlled by the beta blocker and have no other symptoms. One of the symptoms is dyrrhoes which I had for a eeek during my first admission but I’m now back to my usual practise of needing movicol everyday for constipation. I’m on morphine, pregabilin and naproxen.
Has anybody else had anything similar which has been resolved?