Convulsion can be due either to toxing out from contact with high levels of ammonia in the substrate (perhaps it was kept too wet for too long, or wasnt changed when it should have been.) or from low levels of calcium in the blood.
Perhaps you should evaluate those aspects of the frogs care.



Aside from the fact that people keep repeating on the forum that Pacman frogs will seizure when stressed, I have never read this in any source that could actually confirm this being true.