Question about lymphoma?

I have had a small hard lump behind my left ear for about a year now, maybe longer, just about a year ago is when I noticed it. There's nothing else wrong with me, and I looked up the symptoms of lymphoma, and I don't have any of them other than the lump. I was just wondering how long it generally takes lymphoma to spread. I'm kind of a hypochondriac, and I will be asking my doctor also, but I was just hoping someone could tell me if that's still likely? I did have strep throat for about 2 to 3 months when I was 14 (I'm 19 now) and my dentist told me that could have caused the lymph node to scar, and she has one like my from a sinus infection. It's not that I don't believe her, I'm just a little skeptical about it, since it's hard to find information about that on the internet. My dad's third wife died from Non-Hodgkin's Lymphoma, so it seems like a more real fear than many of my worries.