First, I am sorry that your son is going through this. It is hard on your family, he is your "baby" and you want to protect him.
However, he is growing older and going to be more responsible for his actions/reactions and it might be time to look at some other options, such as medication and outside evaluations, that before now may not have been as necessary. You need to start preparing him for life away from the safety and security of your family. You will not be with him at college or when he is at work. You will not be able to"make things right" forever or run interference when he is on the job.
Right now, though, I would docoument what the teacher has said--both from your son and the other boy. What she said, if that is truly what she said, is not right and needs to be addressed. I would have each boy write it out and sign it. Ask for a meeting with the principal to discuss this issue. Remain calm and matter of fact as you state your case. The teacher should apologize to your son for this statement and refrain from doing it anymore, to him or any other student.
I do not think it is unusual to ask if your son is on medication. I work at an alternative high school and that is a routine question that we ask. We find that as kids grow and develop, their medication needs change. sometimes parents/guardians are on top of this and sometimes they aren't. Sometimes parents are hesitant, like you, to put their child on medication until someone can actually document behaviors that occur on a regular basis. We can tell when our students miss their meds as there is a drastic change in behaviors, in class and to other kids as well.
Please look into medication for your son. As others have said in many ways, if your son had a broken arm you would treat it, if he had pneumonia you would treat it. He has adhd and odd with anxiety, so why are you not treating these? Medications could help stabalize him and allow him to function better. You will have to pick which condition to start with as they will generally not start to medicate for both at the same time. Then they don't know which is working and which isn't. They must get one stabilized and working before they can start on another one. Also, your child is reaching puberty which throws a whole lot more into the mix. They may also suggest a different diet or a behavior modification plan as well.
Another poster suggested an outside evaluation from a psychologist. While this may be hard for you to think about, please do talk about it with dh. You want to do what is best for your son, and sometimes it means doing things that are hard to do. The evaluation may reveal some information that will greatly help your son, both medication wise, behavior wise, etc. It cannot hurt to have it done.
I would ask for a reevaluation of his 504 plan. He is older now and there may need to be changes made. Before this is done, it would be worth it to have the outside evaluation done and talk with your personal physician about medication options. If there are no learning disabilities present, he will not get an IEP, so the 504 is the way to go.
Good luck.
) When they are misbehaving, however, I am less inclined to call further attention to it. (Usually, that makes it worse; the kid then acts out more to save face. Or, the kid hates me more and learns less. 
)
