Due to financial problems, my friend gave me her dog to take care of for a few months. He is a Jack Russell Terrier mix, and is about 3 years old. He's been perfectly fine up until about a week ago. Whenever I touch his tail, he would yelp like it hurt. I contacted my friend, and she said that he has never done that before. Anyway, I figured he may have gotten it caught on something, and it was sore or something, but it's getting progressively worse as the days go by. Now even if my arm slightly brushes against even the tip of his tail he starts howling in pain, and and then growling insanely. This lasts for a good minute or two. We can't take him to the vet, because we don't have the money for that. I'm very concerned about for him though. Does anyone know what could be wrong, or how to help?