tantrum

I know this thread has been made so many times before but i really need some help.

I have done thousands of tantrum/backflips on a trampoline, and can land consistently.

i've made 3-4 attempts at a tantrum, with no success and each one seems completely different and ends in a lot of pain.

Firstly do you get use to this pain as you keep trying new tricks.
the second thing is, when i do these tantrums i only go half way round and land on my head, any ideas.
cheers