Symptoms, swollen lymph nodes. etc?

So for about 3 months i've had swollen lymph nodes in my neck, under my jaw, and in my groin area. I considered the possibility of lymphoma until I realized how unrealistic it is that a 19 year old has it. They're hard (some of them) and the other ones are soft. But it's just annoying I mean i'm very thin and tall, about 20 pounds underweight for my height.. It's just annoying I'm sure me touching them constantly doesn't help.. Any ideas of what the **** this is.? Ooh I also smoke alot of cigarettes, that might be a cause for the neck ones.