sorry wasnt trying to cause a panic, but the point is these types of issues, are best noticed and dealt with at the very earliest possible hint of trouble, because like most cham issues, once they are obvious they are usually pretty serious.
like i said it can be hard to determine early or borderline issues via photo, because photos dont always give an accurate representation, so since you were going to the vet anyway, just thought i would mention it , better safe than sorry.
dont panic, but just wondering, do you feed wax worms? the reason i ask is because puffyness or wrinkled joints can also be an indicator of too much fat in the diet. waxworms are higher in fat than protein which generally speaking is not good. waxworms can be as high as 24% fat, thats more fat than any commonly available feeder, which imo, in itself is unacceptable, thats not even counting the fact that they have 32x (not 3.2 but 32) too much phosphorus. so if you dont feed waxworms probably not an issue, but if you do, i would reconsider.
also, dont panic, but imo, he looks awfully full round and tight through the belly. that could be a sign of many things including over eating , even parasites. just wondering, how much do you feed this animal jmo, just for the record, its not good too feed them all they will eat for a # of reasons. imo, i would recommend no more than 5-6 med feeders a day for this animal and no more than 4or5 food days a week.
periods of non food are good, it gives them a chance to digest unprocessed food and a chance to cleanse a few undesirables such as phospohrus. they also hydrate better when their gut isnt full of food. overfeeding can cause a # of issues, including impaction, especially if its an imbalanced diet like mostly cricks. a healthy xanth can easily go for 2 + weeks without food, so going with out food for aday or even a weekend now and then , i would view as more of a good thing than bad
again, dont panic, just trying to give you a heads up before you have to worry about trying to correct those kinds of issues. jmo