Ball pythons have evolved in an environment that is fairly variable with regards to relatively large temperature and humidity changes over short time periods. They are therefore fairly hardy and resistant to environmental conditions that would more significantly stress other python species. It is therefore fairly rare to see regurgitations in Ball pythons caused by husbandry errors unless the variance in those parameters is fairly large. What is much more common is this condition caused by an enteric bacterial infection, especially in imported specimens. If this is the case, oral antibiotics such as Cipro are the best bet.

How many times has this python held a meal down and what is the cage setup you are using? I'm a little concerned that you say it is active, as it should be pretty inactive during the day. Re-check temps as Sonya mentioned and don't wait too long before a vet visit if necessary. As po stated, a large weight loss in a short period of time with a Ball python this young is fairly serious.

Kelly