Large Growth, Either a Really Big Cyst, Or a Tumor.

Hello, I recently developed a large lump on my neck (about 2 inches back from my ear, over the big tendon in my neck.) at first I thought it was just a pimple or a cyst, but it kept growing and growing, its been there for a few weeks now, and is now about the size of a silver dollar, and about a half inch high. As its grown its also become more and more painfull. Its to the point where its hard to turn my neck or tilt it from side to side. As it grew so did my curiosity, and ill admit, ive done my fair share of poking and proding this thing, and it feels like what ever is inside is mostly solid, with a pocket of liquid at the top. It hurts a great deal to touch it tho, and I havnt pushed that hard. The area of this growth has become discolored, light red, and looks like a rash over the lump. Any ideas as to what it might be, and how urgent should taking care of it be? I do not have health insurance, and am currently on the road with my job, so I really dont know what kinda resources are available to me.