My 12 mo old has a dime size painless lump behind and below his left ear. no fever. he is currently being treated for ringworm and underweight. ?

Lymph node: It is likely something called a lymph node, which is a normal functioning part of the immune system. If it's hard, tender, red, hot, or growing, of fails to go away after a long time (a few weeks maybe), have your pediatrician check it out.

Underweight: Review the growth chart in detail with you pediatrician. Lab testing and screening for chronic disorders may be indicated for some children. Provide a healthy well balanced diet and supplemental shakes if needed.