pustule?

the other day i had sort of like a pimple but on my armpit. it hurt and it felt like an ingrown pimple like the size a nickle a little pus came out, thats why i think its was just a pustle, but can it be something worse? is it my lymph node that swollen?

[Cleveland Clinic]

Dear seny23:  If you had a sore red bump that drained pus, it was likely a pimple or ingrown hair and will improve in time.  It would not be unusual for a lymph node to swell in this setting as well as the purpose of a lymph node is to filter out infection/inflammation.  If this does not improve or gets worse, you should see your doctor.