I have a 2 year old chihuahua who has been great at going potty outside. We have a bell that she rings during the day when she has to go. The last month or so she's been going potty in the kitchen and our bedroom! Almost every night! I don't know what to do or why this is happening! She goes out right before we go to bed every night.

I would guess you've had a Vet check her to make sure there are no health issues going on - what did the Vet say?