My son has glands under his arms and he is complaining that its painful. is this normal?

Maybe/ not: You have lymph glands scattered throughout your body. They sift through body serum (lymph) that remove particles like junk from insect bites, some germs, etc. They swell when they are working & can become painful. Armpit glands could swell with events involving the arms or general infections. Rarely they develop abscesses & need drainage. Most swell/work/then shrink over a 3-4 wk period.