Swollen Lymph Nodes (how Long Do They Last?)

As the subject states for a swollen lymph node, how long does a lymph node stay swollen from an infection.

I am curious because I have a 2 hard lumps behind my right ear. I don't remember how long i've had them but they've been there for a while guessing few months. The other day I noticed on the left side of my neck another lump. Not really sure what to think of them all except swollen. My only concern is when should it stop swelling. The lumps are rock solid and are not painlful. I also had strep throat a few weeks ago and I was given antibiotics for that. I'm thinking that if it was from strep throat which was at least 2 weeks ago should have gone away.

I'm not sure if this is revelant or not but I also would have plugged ears due to the fluid build up in my ears. That's what the doctor told me when my ears were plugged. I had this the same time I had strep throat. My ears do not get plugged anymore.

I hope for the best and hope it's not non-hodgkin's disease or lymphoma. Nor thyroid cancer
i hope it could be lipomas. Nothing big.
I don't have the tired feeling coughing or aching feeling.
The lump on my neck is about 1 cm the other 2 behind my right ear are about 1 cm and 1.5ish cm.
The ones behind my ear are located close to each other. The small one 1 cm is few millimeters below the bigger one.
I am 17 years old male.

Any thoughts or concerns would appricieated.