do you know why?

hey i wanted to know why is it that when i feed my bearded dragon big crickets or meal worms he begins to shake his muscles a lot. its like he begins to twitch his arms and legs very rapidly and uncontrolably. hes big enough to feed on these ietms and i know that for a fact but why does he do this? i waste more money feeding small crickets than big ones. last night i fed him wax and meal worms and he began to shake like he does when he eats large crickets. heres a pic of him with and a full grown bearded from Amari Reptiles. please if anyone knows why this occurs please let me know and what i can do to prevent it.

Ok, #1-Mealies are not good to feed, they are high in chitin which means their shells are very hard to digest(no matter the size of the dragon) and can cause impaction, also waxies are very high in fat and not healthy at all, they can be given has occasional treats but nothing more!
#2- What calciums/vitamins do you give him? It could be calcium deficiency, where he did not get enough calcium. It could also be from the mealworms because they are very dangerous.
I would call your reptile vet and get her opinion and you should probably take him in.

Good luck,
Steven