cisplatin is known to cause a lot of problems at times ... the list is long that I read. I am sorry you are having this problem and I hope it is temporary for you.
have not heard of the medication they gave you for it, hopefully someone here has heard of it or used it... but I wanted to stop by and let you know I was wishing you well and hoping for a full recovery. Treatment is bad enough - after effects should not be allowed

i hope you are right handed, since you mentioned this is effecting only the left side.
hang in there and keep us posted on how it goes for you.