A Chronic Case of Stupid

I'm a single parent and I'm about to lose my mind! I have a 16-year-old son who has ADHD and lately it seems like he's also suffering from a terminal case of stupid.

He's not doing bad things and isn't involved with drugs, drinking or crime. He's just doing stupid stuff. For instance, he called me at work from school to tell me that he lost his iPod. Then later, when I was at my college class, he called me on my cell phone to ask me where his Hot Pocket was so he could eat it for dinner. Of course, it was right where it always is. He just hadn't bothered to look. Then he got pulled over by the police (he hadn't done anything wrong, they were looking for a vehicle that matched his car's description) but instead of telling me, he told his martial arts instructor—who happens to be MY martial arts instructor, too! When I asked my son why he didn't mention it to me, he just shrugged.

I'm just about at the end of my rope with his case of the stupids. I really don't know what to do. The thing is, he has ADHD, so he does a lot of things on impulse. That might be the whole problem right there. I've been trying to help him get/stay organized as part of the requirements of his IEP, but for whatever reason, his focus is completely off. We just started a new doctor last night to help treat his ADHD. His old doctor wanted pills on top of pills to counter the side effects of the original medication, which just wasn't working for him anymore. Hopefully, with the new doctor and new medication, he'll be able to focus.

Or maybe all of this is happening just because he's a teenager? We have a decent relationship. When I'm not in class or doing homework, we take martial arts classes together, watch movies, eat dinner, go to the movies, plays and concerts, etc. I don't think he's suffering from a lack of attention.

I want to understand why he does the things he does, but I wonder if we'll ever be able to figure that out. But I'm desperate to know, and totally confused. Can you tell?