There are a lot of things that can be done with cellular nutrition to help kids process all the preservatives and toxins in their bodies from their junk food and environment. Even families eating "healthy foods" are exposed to nice big green produce grown in depleted soils or with too much fertilizer. The gas used to keep our fruits and vegetables fresh during transport and storage is also a problem consumers aren't aware of. I'm in the field, and we're seeing a huge turnaround in all the processing and behavioral issues, such as ADD, ADHD, sensory processing issues, ODD, PDD/NOS, Asperger's, autism, rages, depression, and so on. Omega 3s are not enough. And just taking a few vitamins or a single category of nutrient is far from effective. We've seen people trying to fix things themselves without either the scientific background or any knowledge about how to evaluate products sold in health food stores, and it rarely does anything except clean out the families' wallets. Connecting with reputable food science trends and getting some online education with personal consultation is much more effective.
Some of the moodiness is typical of middle school kids. If some kids are miserable, it can affect the group. But if this is systemic issue, it may be something much bigger.
But if you're seeing a big uptick, I'd look at something in the building - mold and that sort of thing. Have there been any recent renovations with things like ceiling tiles, adhesives for new flooring, changes in ventilation equipment or exhaust, anything in the boys' bathrooms or locker rooms? Are they hanging out after school in a place that is either new or has undergone renovations? We had a huge issue in one of our town's schools - one parent had a very very sick kid but there were others; she spearheaded a massive investigation, fighting the school system, and it turned out that there was a terrible mold problem.The school pretty much had to be shut down. It's now shown up in a second school and it's being taken more seriously.
I'd also take a good hard look at the start of drug use - it's very common in this age group for kids to start getting into the parents' prescription medication and/or liquor, and to be using each other's meds. Mixing and matching meds can be a problem obviously. If some of the kids are going on meds, those meds are now available to others.