You'll see this same reply in the Chameleon Journals, but it's worth posting here, in case it might jog someone's memory, or lead to a train of thought.
If you're thinking produce, is it safe to assume all the affected critters ate some of the same fruit or veggies? And if you use the same food for crickets and other cham food, if there is a food connection, the chams might be affected via the crickets.
Can you recall if all the animals affected ate one particular food (say lettuce, carrots, squash)? This is really a long shot, but some of the produce might have been exposed to insecticides. Even though some chemical sprays are labelled as safe for human foods, they usually need a specific time between spraying and harvesting. I'm thinking possibly the time lapse might not have been enough. Even though humans eating the food might not be affected, we're a bigger body mass than your animals, it wouldn't take as much to cause them some harm.
There's also the possibility of storage inadequacies at the store (or produce wholesaler). Some mold and fungus spores can sit on food and never cause problems, until the right conditions happen, usually in storage. Grain products are often infected with specific spores which can become deadly in humans, so possibly smaller animals can get a lethal dose much faster. Right now I can't recall the name of the spores I'm thinking of, it's common in grain and improperly stored animal feed with a high proportion of grain ingredients. I'll look for the name if you think it's a possibility.
If it's produce or other commercially bought food, there should be other cases in your area, if you haven't heard of any mysterious illnesses or deaths in herbivor/omnivore pets, chances are it's more likely something from your house, or coincidence.
My first step would be to make a list of as many types of food each animal ate in the last couple of weeks, and where/when it was purchased, was it fresh, frozen, commercial brand pet food, etc., and see if there's a common connection. Also consider bedding, air fresheners/sprays used in your house, cleaning agents, and the like, anything that could end up being inhaled or could have settled on their food and drinking water. Another remote possibility is something coming in from outside (open windows) - maybe wind carried sprays, pollution etc.
Have you checked for carbon monoxide (furnaces, gas water heaters, fumes from a connected garage)? And the really far out thought - there is a whole subdivision in this town that was built on a former landfill site. The gases from the decomposition seeped into the houses, and now they're being demolished. Any chance of that around your area?