Infected lymph node in the armpit?

Antibiotics don’t cause swollen lymph nodes.

Call your Doctors office. Let them decide what to do next.

There are no lymph nodes in your cheek, so you can rule that out immediately. It could be completely unrelated (i.e. the cheek thing might be a blocked salivary duct) rather than related. Obviously only a doctor’s evaluation can help decide this, but you can be reassured that it isn’t a lymph node.

why did you get a swollen lymph node in the first place? Maybe that was a symptom of something else which is right now surfacing in your cheek.

Going along with what @atlantis said, a swollen lymph node is usually a symptom of something else. Where exactly on/in your cheek is it? Because you can get these things called sebaceous cysts A.K.A. epidermoid cysts on your face or neck. I have two on either side of my mouth. They’re under the skin and normally painless and benign, but can occasionally get infected. You may want to consult a dermatologist to see if that’s a possibility.