What Causes Difficulty In Walking And Numbness In The Arms?

I am 76 years old, and last year i could walk 6 miles with no trouble 2 or 3 times a week, this year i have trouble walking 2 miles. i walk all winter and this seams to get worse all the time. i quit drinking 1n 1989 and smoking in 2012. I was in the hospital for a check up 6 mounths after i quit smoking, at that time my worst blockage was 40 % my symtems are a num or tired feeling in neck area boath arms and very cold hands, also when i was in the hosital i had the same problem, but it went away after a few days