It's possible it could be a lymph node but not lymphoma. If it has been there for a long time and getting bigger it might be something that you need help with, but lymph nodes do swell and get infected some times (I don't mean to worry you with the thought of an infection or something but it being an infection is a better thought than lymphoma, right?). If you are sick like with a cold or something or if you cut yourself shaving or have acne it can cause near by lymph nodes to swell and be puffy and maybe hurt kind of; it happens to me a lot if I've got a zit or something. I get a puffy lump under my chin or neck or if my skin is irritated from shaving under my arms I'll get a puffy lymph node around there. Cancerous growths, to the best of my knowledge, aren't usually squishy. They are hard and usually not movable. They feel like they are sort of part of all the material making up the area but like it went wrong, not just a squishy, chunky, bubble you can kind of get your fingers around. I know you said that it feels like its attached at a certain point but, in my opinion at least from your description, it doesn't sound like its really solidly part of something. It has to be attached to you somehow to be there at all, you know? Otherwise it would be like a foreign object that just appeared by itself which it's not. So being attached a little bit only makes sense and I don't think it is the kind of "attached" that hints at cancer. I'm not a doctor or anything but I hope that helps a little bit.
I've had lots and lots of pets who all had various health problems, some of which were cancer, some of which were lumps that turned out to be nothing. If my experience with my pets is good for anything. lol When my cat had cancer it was obviously different than the others who had had harmless lumps. The one with cancer had a really hard lump that got bigger and wasn't just attached to her skin but was part of her skin; like her skin went wrong in that part. You couldn't move it with your fingers or anything like that. A dog and one or two of my cats have had lumps that were harmless and they were squishy and movable and pretty round.
I hope you feel better and that it's nothing. I know how scary it is to think something might be wrong.