First off, 7th grade is tough no matter what your challenges are, so hugs to your DS.
Second, while I don't have concrete advice, I'm curious about side effects with the medication - is mood-swing one of them? Could he be especially susceptible because of your family mental health history? (DD is on Adderall XR, and mood swings are one of the side effects that are on my "call the doc immediately" list.)
I see you've called his pediatrician, which I think is especially important - we experienced some inconsolable crying while trying to raise DD's medication dose two years ago, and this is a listed side-effect with the meds she's on - but do call again. I don't think you're overreacting - the meds given for ADHD are so tricky to get right and if they have any side effects, as I'm sure you know already, it's important that your team is aware of them as soon as they crop up.
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Liz
DD (3/2010)
"Make mistakes! Get messy!" - Miss Frizzle