It is like riding a bike.....a couple of years ago I had a surgery on my hand and was unable to ride for almost three months. When I got back on it was like I has just ridden the day before.
Welcome to the wonderful world of having the internet occupy your time. Although I have been told my humour has resorted to

and that I need to hurry up my healing.
Keep your fingers crossed....maybe it's only strained muscles.
If you want a cheap easy fix to see if a back rest would help...place a rolled up sleeping bag right behind your seat and secure it with bungees or something. Even my milk crate served the purpose on occasion.
