First of all I would advise you to see your Dr and have this examined. This could be a lymph node since it's the appropriate size as you described OR it could simply be an infected hair follicle. When you discover something of this nature it isn't usually wise to just wait and watch; it's best to get a professional opinion as it may be easily treated. It is the function of the lymph nodes to enlarge to some degree even when there is an infection in some other part of the body and they rarely return to their normal size. Please see your family Physician for an exam and opinion as to the cause of the lump. Regards .....