Offering an alternative prey especially such as gerbils is rarely the right answer, especially when the prey is expensive, not always easy to find, capable of inflicting more damage than a rat or mouse, and hard (almost impossible) to switch back from, forcing the owner to maintain their animal on an expensive prey which make rehoming (should it happen) almost impossible.
In most cases is related to husbandry?
To the OP
Given she is an adult she can go of food for months the key here in your case is to correct a few thing to see if it can help her resume feeding a little faster.
First I would put her in a 32 quarts tub the more secure the better.
Second I would address those temps, they are nowhere near where they should be, cool side should not fall under 75 either, ideally you want to maintain temps of 78/82 on the cool side and 88/92 on the warm side.
I would also recommend no handling until the animal eats for you.
Now those changes are necessary however she might still not resume feeding right away since they often stop eating during breeding season as well, however you need to make sure your husbandry is optimal.
It's not uncommon for adult to stop eating after a change of environment (they are more likely to do so than younger individuals)
Adults can fast for a long time and still hardly loose any weight, if she does lose a lot of weight (and you need to monitor her weight) than something else might be going on and a fecal would be highly recommended.