Hi there my son is 11 as well. We have been on all kinds of things since he was diagnosed when he was 5. I find that the mornings and evenings can be hard.
I have always been told to give the meds 2 weeks and to see what happen or how they “adjust.” However, if it is too much to handle you may need to call his dr. and tell him the issues and see if you should keep trying or discontinue the meds. We tried one med before and the side effects where so awful for him that we pulled him off within 2 days.
For my son I find that the rebound effect is worse when he is on a long acting medication like Vvyance or Addreall Xr. We have put him on a short acting med that only lasts 4 hours and this helped with the rebound effect. Hope this helps!