I started Amantadine in March of this year for fatigue and yes, it made me dizzy & loopy too, but it also made me less stiff and less fatigued.
However, I was noticing most of the time my heart was racing & I was freezing...I spent alot of time wearing fleece in the summer & socks to bed. I was also on Copaxone at the same time, so that may have been part of the problem too.
My neuro took me off both drugs 2 weeks ago & I am stiffer than I was before I started & dizzier to boot:( I also went through a battery of heart tests /monitoring & my gp believes it was the Amantadine/Copaxone that was causing my issues. No more tachycardia, although I still get the chills sometimes. Fatigue is still there, but I feel that Amantadine did not really help that issue for me for very long, hindsight being 20/20.
With every drug, docs weigh the pros & cons and if you can live with the side effects, stay on it, if not, don't compromise your health. I realized the benefit was not as great as I thought it would be, I guess I just have to stretch more
I hope this has helped & good luck.