What Causes Chronic Tremors In The Hands Despite Taking Propranolol?

I am a 54 year old male. Recently I have noticed the muscles in my left hand and baby finger get very rigid when I’m sleeping. (cramp like). This wakes me up and takes several minutes for my hand to rest and go back to normal. I also feel like my left arm is stiff and I usually massage the muscle for relief. I have also noticed I forget things a little more often or ask the same question more then once. I’m tired most days even though I sleep 6-8 hours a night. I was diagnosed with essential tremor 20 yrs ago and take 80 mg of propranolol daily, but tremor is now worse in both hands only. I am very overweight, I have an uncorrected umbilical hernia, use to drink alcohol heavy but no longer drink. I do have high blood pressure but a combination of the propranolol and norvasc seem to have it under control. Any thoughts on what might be effecting me? Thank you!