Your kitten may seem poorly because of an inner ear infection if you speak with a good local vet it could cost less than £20 for a injection of antibiotics that will fix the kitten up quickly.the heart rate is probably high due too stress of feeling like failing all the time and would be the reason the kitten is this balanced.
My Kitten Is Always Dizzy, Never Keeps Her Balance, She Is Always Falling Over Running Into The Walls And It Seems To Me Her Heart Rate Is Very Fast, Why?
It seems to be a neurological disorder. If you can not afford a vet, I would suggest that you contact your local area humane society. They can help you in this regard, and even can find you a vet with very little or no fee.
Did the cats whiskers get cut off of one side. If the cats whiskers are uneven it will cause them to be unbalanced!
I'm no expert, but maybe its blind. Or deaf. Have you taken it to the vet lately? I would do that.