The best i could come up with is it may be an abscess.. If you read below it states that it can be agrivated in times of stress.. breeding for examle..
I found the following info that may help.. ~ Mike
What is an abscess?
Abscesses are localized infections that generally occur in conjunction with systemic infections. The site may swell noticeably, or the abscess may reside well into the underlying tissue with little change in the skin above. there may be slight swelling which begins to ooze a yellowish liquid which may form a crust. As the skin stretches over the underlying swelling, the scales are moved farther apart and the skin in between may be seen. The skin may be reddish with petechia (burst capillaries) or crusty with dried serous fluid.
Why do abscesses form?
Generally speaking, bacteria that gets into a wound, say a minor scratch or puncture wound, from claws. The body's immune system is unable to successfully fight the invader off, and so the wound becomes infected, forming an abscess.
In healthy animals, the immune system marshals a defense and kills the bacteria before it can cause a problem, forming antibodies to recognize and fight it again.
A stressed animal has a weakened immune system. As it cannot as effectively fight off infections, some microorganisms will manage to proliferate to the point of causing illness. (This can happen to the normal load of gut microorganisms, which is how healthy reptiles end up needing to be treated for excessive loads of worms or protozoans.)
Captivity itself causes stress, no matter how perfect the captive environment and apparently well-adjusted the captive animal. Changes in the daily routine, introduction of a new household member or pet, moving to a new location, seasonal changes such as breeding season, etc., can affect the reptile's stress levels. Stress-related problems may follow relatively quickly, or may not manifest until weeks or months after the start of the stress period or stress event.
Stresses can include emotional stress such as being moved to a new enclosure, having the entire enclosure moved, changing owners, too cold, poor diet, breeding season, etc.
Treating Abscesses
Abscesses that occur in fleshy tissue can be lanced with a scalpel, the caseous pus removed using dental or bone curettes and swabs, and then flushed with an irrigation solution, such as 1% chlorhexidine diacetate (Nolvasan).
Even if all the caseous pus is removed from the site, and the site is kept open and irrigated daily and treated with systemic and topical antibiotics, more pus may form at the site, sometimes within a couple of days of the initial treatment. While this can happen even when the reptile is being given systemic antibiotics, it is more likely to occur when only topical antibiotics are given.
Failure to start antibiotic treatment may result in a worse infection if the site is not cleaned out thoroughly. Even when on antibiotics, particularly resistant infections may cause repeat abscesses to grow. This is because, even though the antibiotics used first are broad-spectrum (effective against a wide range of bacteria), the bacteria causing the infection may not be responsive to that particular antibiotic.