Dear Chevvy,
I'm sorry for your experience.
A second opinion or change of Oncologist, seems necessary for your peace of mind.
Since your Breast Surgeon supported hormone therapy, He could refer you to another one.
Perhaps the choice should be yours, after full information.
You said you have been dizzy and had a fall.
Has your blood pressure been checked?
If your blood pressure has lowered, perhaps your body will adjust.
You may need to be mindful getting up from bed or a chair, slowly.
I'm not on Tamoxifen, I'm on Letrazole(tolerating OK)
Good luck sorting this out.