There's no turning back bro, you can't take a back route to iOS 6.1.2, you fell right through the thin air. You cannot jailbreak the iPhone 4S on 6.1.3 as one of the exploits used by the evasi0n jailbreak is patched. You have to stay on that iOS until further notice and a jailbreak is released for 6.1.3.
Many thanks,
Software