I have two kids. Both were doing the same exact thing. Everyone was telling me ADD or ADHD too. Same thing my parents were told when I was a child. ITS NOT ALWAYS ADD OR ADHD!!! I'm 27 and after a lifetime of misery I finally found out the truth. Instead of ADHD like they were told, it was Aspergers. No wonder the meds and 'treatment' didn't work. An unbelievable amount of kids in my generation actually have Aspergers not ADD or ADHD. Doctors back then didn't know about it. It was more widespread as of 1993. Aspergers is on the Autism spectrum. High-functioning. I'm highly intelligent, but socially have to mimic and adapt which doesn't always work. As for my kids, same behavior issues. After the hell I went through as a kid and not learning the truth until I was an adult I was determined to prevent that fate for them. I talked to their pediatrition and she referred them to speech, behavioral and occupational therapy. Both have made a huge improvement. I 100% recommend therapy. Medical Card here in KY has paid for most of the bills. I noticed though they were having some days better than others. That's normal, but I began to notice a food link. I did research online. Casien in dairy, gluten and sugar all can contribute to the bad behavior. So, I started them on a multi-vitamin and (dairy-free, gluten-free) pediasure and eliminated dairy and switched to soy and rice milk. Then got rid of gluten in their diet. It's very suprising how many things it's in once you start to look. That means no bread, cookies, cakes, pasta, cereal, crackers, chicken nuggets or breaded items, anything with wheat, barely or rye. Within a few days HUGE improvement!! You would have to see them to understand. I started the same diet and have more energy, am less hyper and finally no more stomach upsets! Thankfully Wal-mart and places are carrying more Gluten free foods like rice crackers (my husband us on normal diet and likes them), cereal etc. To finally have a sense of peace and normalcy is worth the learning curve with this new diet. My Husband thought I was crazy at first and punishing them. Then after a few weeks they were calmer and getting quickly smarter, then a family member gave then pizza and that day was literally hell....back to screaming, tantrums, acting out, etc. As for the junk food, don't buy it. If it's not in the house he'll have to eat what's there or be hungry. Chocolate pedicure, fruit smoothies, apple-cinnamon rice cakes, peanut butter and apple slices (or carrots etc), raisins, popcorn and things are healthier and less sugar. Mine still get candy occasionally, but to where it's a treat and appreciated more. Trust me, get him the help my parents couldn't get me. I was raised mostly by my Grandma because I drove them nuts...eventually she tried to get me some help, but there just wasn't much then. With the resources now, ge can be an amazing child...no longer an animal trapping you in his zoo. Good luck!
Edited to add: Also consider the circumstances of why you have custody. He could be acting out. I would definately get him to a therapist so he can talk to someone that ge doesn't have to worry he'll get in trouble with. It's easier to talk to someone neutral that you don't live with. I had bad behavior towards my Grandma when I first lived with her.