I found that the flexaril works real great for a few days then tolerance rapidly develops. I ended up needing to take 8-10 at a time. It made my muscles so tight and spastic when didn't have it, and when I finally dosed the effects only lasted for about 2-3 hours before the pain came back. Its worthless and only makes the problem worse in the long run IMO.
The tizanidine didn't really do anything (not even when used IV) except make me very sleepy. It had little to 0 impact on my muscle pain in my neck.