Same with dear grandson. Tummy hurt, hands shaking, heart rate high...not fun to watch. And he definitely has trouble with sleeping. We asked about melatonin and his doctor said it can make things worse. I don't know, but we are trying other sleep hygiene things: warm milk, very structured calming nighttime schedule, etc. And yes, his growth has slowed. He doesn't complain of tummy aches anymore, and hasn't since the first month or two. We do remind him to drink a lot of water because of the dry mouth stims can cause, and this is hard on the teeth.
He's been on stims for quite awhile now (since Nov. 2011) and we have adjusted our expectations of when he eats and how much. We make sure there are lots of nutrient dense things to eat in the morning and and he'll even have two dinners: A light one when the rest of the family eats because he really isn't very hungry, then one closer to bedtime because by then, he's really hungry. Even with the stims onboard, he has been eating like a house afire the last few weeks, so I'm guessing a growth spurt? We hope so as he is a wiry little dude, too, and his peers are passing him up height-wise. With us, it's been balancing the positives and negatives. We want him to take a medication vacation this summer, but his father, with whom my daughter shares 50/50 custody won't allow it, so that battle has yet to be fought. There have been many positives for him, especially at school, but every child is different. Our guy has something else going on, too, and the anxiety and rages make us wonder about the stims. It ain't easy. I hope your little Tweety Bird adjusts okay and it is successful for her.