lump at the bottom of arm pit

[Becky]

I kept picking Zach up tonight and he would lunge at me and then really bit me anywhere he could. When I went to put his pj's on I felt a dime sized lump under his left arm pit. Do you think this is serious? Could it be because he had the flu the last 2 days? Should it hurt him that badly if it's not serious? He has a couple on his neck, but the ped said not to worry if it's above his shoulders. Oh my poor Zachary

[Sam]

Does he still have the lump under his armpit? Have you shown it to the ped? When the ped said not to worry about the ones on his neck did they say what they thought they were?