Thanks for your reply about the Periactin. I'm going to talk with the GI nurse practitioner about the dosage specifics. We were only told to give an AM and PM dose with no specific timing. My DD was also very sleepy at the beginning but it seems that has changed as well. She's been using Nasonex for sleep apnea so I don't know if that could be causing a problem too.
If you don't mind me asking, what formula are you using? We've been using Boost Essential (Resource Just for kids) 1.5.