Hi thanks for your question.
The grape size swelling which you have under your chin is most probably an enlarged lymph node
called as submental lymph node.Lymh node get enlarge when there is infection in their vicinity.
Since enlaged lymph node is associated with low grade fever
and sweats.these symptoms are suggestive of tuberculosis
Consult some physsician and get you sputum examinationa,chest X Ray
and FNAC of this swelling done to rule out or confirm the diagnosis of tuberculosis.
Hope this answers your question.