Opps, just noticed that you are the original poster which answers my question about what grade he is in now. And thankyou for the information about his medication. That still might be part of the answer, but thats for his doctor and you to figure out. The video link I posted will help with that.
A good question was raised by one of the above posters. Third grade went really well! Why??? Is this more a problem of the teacher being stricter or demanding more? I would talk with the 3rd grade teacher and see if she can shed any light as to why things are not going as well. Has his medication changed between 3rd and 4th grade? How about his sleep habits? I would also try and talk with his new aide to get her impression of what is happening in class.
Finally, you said that they want to keep him in his seat and work. There are lots of studies that show that kids with adhd need to be able to roam or move. fidget gadgets help, but moving helps the most. In his IEP, is it written that he can get up and move around? And, of course, many times the correct medication will help with the hyperactivity of movement. Humm, that leads to one other thought and that is about Sensory Processing Disorder. It can look a lot like adhd, but it is treated by an occupational therapist and the traditional adhd medications will not help that much – although it is not uncommon to have both.
Here are two good links. And I have several more if they are needed. But take the time to check these out – it would answer a lot of what is going on.
I hope this helps. This has to be so frustrating for you!