Very, very underweight chinchilla needs to gain weight!

[Chin_Parent]

We got this chinchilla in and she was underweight when the previous owner got her and on top of it she went through two pregnancies back to back (and I suspect she had pregnancies before that as well). She's incredibly skinny and has a hunch back. What can I give her to make her gain weight? I've been feeding her her pellets (Purina Sho) as well as critical care from a spoon, since she loves it and gobbles it down. I was considering getting her the weight gain supplement from Fuzzies Kingdom, any other suggestions?

 

[Chin_Parent]

She also has hay and hay cubes in her cage, but she doesn't touch them.

 

[jbcstratton]

Try some alfalpha hay.

 

[ticklechin]

Alfalfa hay needs to be introduced slowly or loose poo can happen.