I occasionally get sneezing fits where I will do easily a hundred in a row. It seems to be triggered by some little particle lodging itself in just the right spot, as I have learned the only way to stop it is to sneeze through the nose forcefully.
Sleep, Benadryl, music all relax muscles.
Squeezing your nose does help for constant sneezes. So does taking a shower or splashing cold water in your face. Those are all muscle related.