The cyst you spoke of is more than likely an abcess called Caseous lymphadenitis. It's often on the neck or shoulder and will grow until it bursts. I understand it to be a major disease of dairy goats. In the book "Raising Milk Goats the Modern Way", by Jerry Belanger, it is suggested that you isolate the animal, open the abcess making a small incision under the lump and carefully squeeze out the pus. Do not get it on your skin or on other animals. Collect the pus onto a paper towel and burn it. (This is a highly contageous disease). Inject with 100,000 units of penicillin with dihydrostreptomycin. Personally I'd take mine to the vet and have all this done if it's convenient enough. The book I menitoned is terrific. Also you can email Vicki McGaugh at lickilonesomedoe@hotmail.com.
she knows EVERYTHING!