My 6 1/2 week grandson has a painful swollen lymph node in his groin... in hospital doctors can not figure out what is causing this?

Poor thing!: Tina, I'm sorry your grandson is in pain; There are many possible causes of a mass in the "inguinal area." Hernia, hydrocele, lymph node inflammation, and undescended testicle being the most common. If not already done, I would ask for an ultrasound. Watch for fever, as any fever over 100.4 rectal can be a sign of a spreading infection in a 6 wk old child. Hope ur grandson feels better soon