Lumps under jawline can either be lymph
nodes or salivary gland
swellings. If it is of a short duration (less than 3 wks) it is most probably be a lymph node. If its not painful, no need of antibiotics,usually resolve on their own. Next would be to get done a FNAC (cytology) if it persists by the time you see your doctor in next 3 wks. In case if she develops pain in them, you might have to start antibiotics.
Salivary swelling due to infections are usually painful.
Dr Bharath Rao