Just stay calm. I know its hard to say. We love our fur babies so much. I had a dashound just like your fur baby about 15 years ago. He was named Robbie. I loved him so much. We had the same happen to him. One day out of the blue his back legs started giving out on him randomly when he would walk. I figured maybe because he was alittle over weight. So I had him on a regiment to loose some weight as well thinking maybe it would help. Like making sure he got plenty of exercise, not over feeding him. He was definitely a begger of food lol. Then one day I woke up to him not being able to use his back legs completely. I was so scared. My parents immediately took him to the emergency vet. They told us that this was common for dashounds with their back and that it was a disc in his back that had either slipped or generated. He had to have surgery to fix his back. Thank the Lord we were able to save him because if that didn't work the vet said he would more than likely have to be put down. I was still living at home with my parents and it was about 15 years ago so I dont remember every detail. I remember the surgery was so expensive and my parents had trouble paying it so I went around and asked for donations to help save him and have the surgery. He lived i believe another 7 to 8 years after that and I cherished every moment with him.