Seems you’re in the midst of discovering why I do not recommend offering gerbils to ball pythons. Gerbils are like crack for BPs. Once you get one going on gerbils, it can be impossible to get them off.

I hate to say it, but your PETCO friend did you no favors. There is a very good chance that your snake would have broken its fast in its own time. Now you have two problems.

My advice is three fold:

1) Stop feeding gerbils.

2) Use the tough love approach to getting her back on mice or better yet, rats.

3) If the snake is going to starve its self to death, start breeding gerbils.

I can site two cases where someone who fed gerbils now has a breeding colony because their snakes simply will not eat anything else.

Good luck!