Flux,
In reading the posts so far, I see lots of advice based on complete guesses, and only one valid course of action based on logic .. to see a vet.
Could it be fish flakes, supplementation, etc ? Sure, It could also not be too. I have seen "wobbles" about a half dozen times in panthers. That would be out of several thousand candidates through the years. I have only limited experience with veileds, having worked with about 100. Were any of them the same as the wobbles you see in your chameleon ? Not a clue. I can't even say that any of mine were caused by the same agent. I have seen it in five juveniles and one adult, all lasting 2-6 months. The adult and two juveniles recovered fully with no recurrence, and no change in their regimens. Three juveniles died. I can't say with certainty that their deaths were linked to the wobbles, but the possibility has to be there. In all the cases, we saw no link to any causitive agent. It appeared random. In every situation we had many other chameleons linked genetically, in the same husbandry conditions, same food, proximity, etc. etc., and not even a hint of a link to a cause. Again, all observations pointed to a random condition. One asset of having lots of critters is that deficiencies in genetics, husbandry, etc, become apparent in quantity, and aid in the inclusion and exclusion of common threads, and hence, causes.
Diagnostics and vet care are not inexpensive. But its also the first best way for you to get accurate feedback. You could try any change in husbandry that caught your whim, but its hard to know what to fix if you don't know what is broke. I have personal experience with the use of fish flakes as a gutload over the course of years, with hundreds of animals. Never seen an epidemic of wobbles, much less a single case in an animal on flake-fed crickets. That is not an endorsement of fish flakes, just an observation valid to some of the discussion here. As diagnostics for reptiles improve, and we avail ourselves of them more, we would only hope to connect the dots a little bit better in the future. Until you seek them out, I would caution against some of the half-cocked solutions. Three-quarters cocked is better

Good luck.