The location of the swelling is important in determining the possible causes. Swellings in the neck could be enlarged salivary glands, an enlarged thyroid, or activated lymph nodes.
Lymph nodes may become noticeable in several parts of the neck -- front, back, sides, upper neck and lower neck. Salivary glands sit in the upper part of the neck just under the jaw and in front of the ear. The thyroid gland straddles the lowest part of the neck near the Adam's apple.
Is your swelling confined to the area close to your Adam's apple?