Second thought, if no apparent brain issue, might consider physical theray or occupationa therapy with professionals, will need Dr.'s order for payment.
If the tumor is gone, you might post the ask an expert Neurology forum.
This is a link to Medhelps archives on brain tumor issues. We don't take the kinds of chemo that your dad is on and it would be irresponsible for anyone on here to anwer your post. You need to discuss this with his Dr. I really am sorry your dad has to go through this. I will report this as miscategorized and maybe medhelp will move it to a forum that will be more helpful. When they move it they will send you an email telling you where you can find it. Good luck to you and your dad.
http://www.medhelp.org/forums/neuro/archive/Brain_Tumor1.html
Jan