My 9 Year Old Son Has Had A Cough With

My 9 year old son has had a cough with no other symptoms for about a week. Today he developed a pea sized lump inside his tongue toward the tip in the middle. It is very sore. By tonight is has doubled in size. Could this just be a swollen gland or should I take him to the Dr. There is no visible sign of the lump to the naked eye.