I think what you are talking about is called a wolf its caused from fly eggs getting under the skin. Its very common in out side animals out in country areas. Rabbits and other animals can get them as well. If you have gotten it out the best thing to do is clean it good. And watch for more to show up. I have not known of any animal dying from then if they have been gotten out. But keep an eye out for more lumps.
You need to get her to the vet immediately! If it is what I think it is it may be contagious! Where was is located and how did it come out?
It's most likely an egg sack of worms.You should watch your dog more often.