I'd have to agree with those who say this is not normal.

Excitement or a burst of energy AFTER using the box may not be a sign of a problem, but it also could be.

But running before and meowing a lot while going, very well could be a sign of a health issue going on.

How is your cats' stool? If it's hard and dry, it could be causing pain to actually get it out. If it's runny, soft, smelly...there could be stomach pain going on while the cat goes, much like when you have a bout of gastroenteritis or diahrea.

If you haven't had a stool sample checked, do so. If you feel your vet is not addressing the problem in a caring, concerned manner, find another vet.