Can't really tell much from the photo. But Carpets often look unusually swollen around the pits/head area before shedding. If he's not in obvious decline or discomfort, wait until after he sheds. If it is still swollen or looks infected, it would most likely be stomatitis which would require oral antiseptic treatment to the area. That, along w/ heat and dry caging usually clears it up. Antibiotic injections may be necessary if its an advanced case. Either way, you'll have your answer after shedding.
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