How come sometimes I can walk and sometimes I cannot with MS ?

When I had the crossing of eyes, dr's said it was "dip-lo-thia) I wore a patch and I could see fine. every day I would switch it to strengthen each eye. The eye muscles where being lazy. Even now when I cross my eyes completly, one eye is slightly "not as crossed" I had so much fun with the eye patch, I painted it differenc designs with faberic paint and everything!! Optical-neuritis is what I was told. It went away after a time, same thing with the walking. I guess it depends on how tired you are (physically, mentally), what the tempertaure is, (I do better in heat than cold) but that is just me. I hope this helps