What Causes Swollen Lymph Glands Under The Jaw?

Granddaughter 25yo had had swollen lymph gland in left or right upper neck - under jaw. swells from time to time. Has taken antibiotics - no infection, no tenderness. She now show sever more nodes in the neck area which are also not tender. She is married with one young child of 2yoa. She is a vegan as of late but had the 1st lymph node many years before she gave up meat. weakness in legs. She does do yoga and walks often. Dr. in England scared her to death mentioning AIDS. She has never done drugs and has had only relations with one man her husband . She is scared to death. Air Force is not one to send out to specialist. can you help me?