Her ears flattened back some and she started leaning to one side, when we went to check on her she started to move but her back legs where thumping the ground very fast and she was running lop sided. When we got her, which wasn't hard and her actions reminded me of someone who was drunk, she was very calm and just layed in our arms.
There's a possibility of a seizure and/or stroke from what you are describing ... not being there or actually seeing it, makes us have to "guess". There is no substitute for a check up by a good licenced exotic pet veterinary that is familiar with chinchillas.
{a.s.a.p.} Make a list of what she did and what she had to eat/drink in the 24 hours before it happened, it is easy to forget, so wright it down. The vet will probably run blood tests and/or he/she may tell you it could be a one time thing, but if it happens again, bring her in immediately.
The play area should always be cool and a chin-chiller stone in the area is good to have for them to get on, if they should get over heated. A chin-chiller stone is a marble or granite tile that will stay cool and absorb the heat from the chinchilla to allow his/her body to cool down quickly. (The thicker the better. The thicker it is, the longer it will remain cold/cool.) These can be found in most stores like Home Depot or Lowe's in the flooring department. You might want to ask about a marble entrance tile ... often these can be 1/2 to 1" thick and long enough to have them cut it in half. Ceramic pots with a large base and straight sides can also be used. If non of those are available, a mason jar filled with ice cubes, metal lid screwed on tight can also be used.
At least one of these is almost a must, when the little one is out playing ... especially a new chin ... you never know ... it could have a heart murmur and need to be more restricted at play time for this reason. Shorter, but more often play times with chinchillas that have a medical problem is often advisable. I would never put one down to play in a room that was above 70 degrees. Scheduled playtimes are best ... the little one has an inner clock ... usually, if you are even 10 minutes late, they will let you know it.
Have you shampooed the rug, cleaned the floor or sprayed for bugs in the last week? If so, there could be residue left from the chemicals. If this is a possibility, you may want to start by cleaning the bottom of here feet and paws with an alcohol prep pad or a clean white cloth or paper towel with alcohol on it ... using pydeliate in her water bottle instead of water may also help get her electrolytes more balanced.
Any time you do shampoo the rug or mop the floor, for safety sake, make sure to go over it several times with clean water and allow it time to dry thoroughly before your little one is let out to play.
Chinchillas can get into the smallest of places, keep this in mind when one is playing in the kitchen especially ... chemicals may be behind/under the stove and/or refrigerator that you may not be aware of ... these are two of the favorite hiding places for most chins.
Now, we were starting to panic but noticed her body seemed a bit warm so we first grabbed some ice packs, wrapped them, and set her in the carrier we had with them around. She seemed to just lean against them and lay there.
If it is a seizure, you want to protect them from hitting things around them (a circle of pillows is good), but do NOT restrict the movements, you can cause more damage than good. Once it has stopped, it is usually good just to hold her close to your heart (your heart beats tend to relax and reassure a chin), but do not allow her to get over heated by your own body temperature ... I like to lay on the bed and let them snuggle with me ... they usually move a way if they get to warm, then come back. Seizures and strokes are scary, even if you know about them, at the time, you don't know and you have no control over what is happening ... this is not a good feeling ... I've been there to many times myself.
Please keep up posted on how she is doing and what the vet says.
Jo Ann