Anyone see legs get weaker on Ampyra?

My new Neuro prescribed Ampyra to try and improve my walking. After a few days I felt like my legs were weaker. I went off of it for a week and then tried it again and the same thing happened. Now the weakness seems to be hanging on even though I stopped the drug.
Has anyone had good results from Ampyra?
Did your walking get worse before it got better?
Thanks.