So sorry to hear that you have tremors esp when so yoiung . I am a fellow sufferer wiht hypo thryoid which started 22 years ago after a virus. Diagnosed as having Hashimoto's. Like you I have tremors and soemtimes whole body shakes.
For the last 2 years my hands are tremoring so badly I cannot do hadnwritng and make SO many typos I've almost given up writing emails as it takes me hours to do (big contrast to the past). It's awfully depressing not being able to bang out some news easilyand really fast with virutally no mistakes at all as I used to.
To my knowledge (MSc , MPhil and PhD in neuropsychology, and LOADS of research) low tyhroid could be the cause but it's uncommon, uless you are also hypoglycemic (low blood sugar when your dody needs to feed). If you are on a strict slimming diet that could be part of the cause.
I do feel for you as it is worrying that beta blockers aren't working for you as they are effective for shaking. I have to take clonazepam and procyclidine as I also suffer from blepharospasm (involuntary eye blinking) whih has spread to facial, oro-mandibualr and esophagus as well. I'm in my 70's and I can expect some aging deterioration, but lately I've demanded to know if I have Multiple Sclerosis (MS) but the neurologist I see is unhelpful and dismissive of this. I have virtually ALL the symptoms incl this shaking and movement, bowel and bladder probs as well as serious eye problems. My hearing has gone fairly recently and this was a big shock as I had very acute hearing. I've even been goven hearing aids.
When my thyroid problem started I had a lot of help and many many tests and ws finally diagnosed with Fibromyalgia and Chronic Fatigue syndrome. I think though the diagnosis should have been MS from the start as I've suffered from pain, stiff muscles, and eye problems during hese past 22 years
I was living in New Zealand aand the time and the medical help was supreme. THe test showed I had Hashimoto's - an auto immune disease of the thyroid.
Had hundreds of tests but an MRI was not avaiable in 1992. From my research there are many people wiht low tyhroid who go on to develop MS, and sometimes I think (like many med experts) that the diagnosis of Fibromyalgia is just a fake diagnosis as it is so often belived to be a false diagnosis for hypothyroidism which in itself hs wide ranging symptoms. I've had a session with Dr Barry Peatfield when my symptoms started to really interfere with my life. He's very kind and helpful, and I now take "natural " T3, and also adrenal support, as well as the T4 which is all the docs will give you.
Let me know if you have other symptoms and get back t the GP and let them know the B-blocker just isn't working and that you want testing by a medical neurophysiologist (sometimes called med physio or med physics) They can test well for MS and othert neurological symptoms.
Wishing you all the best, and do let me know how its goes.
Warm regards, Maggie PS Sorry about the typpos but you'll know why.