Hi, i know that I’m a bit late to comment, but how is your guy doing? Did you manage to get a fecal float done? Unrelated to what you’re asking, but relevant: around the beginning of February, I noticed my chameleon had diarrhea. Had a fecal float done, and I am now treating him for Coccidia. That being said..
Your own cham’s runny poop does not automatically mean coccidia. It is not at
all my intention to freak you out - it is just that I am speaking from direct personal experience, and I want to highlight the importance of finding out the cause of runny stool if/when it happens. Generally speaking, unless your chameleon has been eating lots of juicy feeders (like hornworms or silkworms), runny stool is considered abnormal and warrants a fecal float done by a vet. Be sure to have it done by a vet that is knowledgeable on reptiles, as there is specific information you’ll need to know about the results of the test (such as which parasite your chameleon is infected with, if any, as well as what his current parasite load is). You’ll also need your vet to get a weight on him in case he does end up needing medication.
Beman is 100% correct that runny stool and poor appetite *may* be indicative of a parasitic infection, and you’ll want to find out for sure assuming you haven’t done so already.
Again, I know it has been some time since you posted about this, but my first bit of advice would absolutely be to stop free-feeding bugs. Feed everything from a cup clipped to a branch or vine, or use something like this:
https://tkchameleons.com/products/shooting-gallery
In the event that your cham‘s runny stool was in fact caused by parasites, it is crucial that you eliminate any opportunity for his feeder bugs to come in contact with his poop/any surfaces in his cage contaminated by his poop (like branches or vines below where he basks that may have been hit by falling poop). You’ll also want to improve your gutload! Ditch the potato and replace it with sweet potato. Use leafy greens and a variety of other vegetables with it. To make things a little easier for you, I attached a chart with options. I personally use a mix of collard greens, mustard greens or bok choy (usually whatever is available at the store), carrots, yellow squash, green or red bell pepper, sweet potato and blackberries. I blend it all up with a bit of water, freeze it in ice cube trays, thaw it out completely and serve it to my cham‘s feeder bugs as a paste. I’ve also used
Repashy Bug Burger with good results.

The goal here is to feed your chameleon the healthiest possible insects. The healthier his food is, the healthier he’ll be and the better condition he’ll been in to fight off any possible infection (along with medication, should he need it).
I hope he’s feeling better!