Hello, first be calm, beardies are almost bullet proof. The weather will affect the movement and eating of dragons. If it is getting very cold where you live, the dragon is just slowing down for winter.
Once my dragons hit a year old they hibernate for a couple of months, during the winter. They did this even when I lived in Southern California. Now with the weather in Montana (25 right now) they will almost start to hibernate by themselves.
Prior to the period of hiberation they need to have all the food out of their systems. Mine do not eat for 7 days prior to going to sleep. I also soak them in nice warm water to make sureall food is out of them. Dragons swin really, really well!!
If your dragon is healthy, and normal weight, they could go for a couple of weeks without food. Also I have never seen a dragon starve if it was able to eat. Give it the very warn 20 min swin then offer food. PM me if further problems.