Cancerous nodes are firm, fixated in place (you can't push them around easily) and painless. The only way to know what is causing yours to swell is to do a CBC blood count looking for increases white cells which would indicate that your body is fighting an infection (not cancer), and if these nodes fit the description above, to do a fine needle biopsy of a few of them to sample cells from inside them for a histopathology look to see if there are cancer cells within them.

It was very common, especially 10 years ago, but even at smaller less experienced institutions today, to have what we term occult oral environments or unknown primaries. Today that is less so, especially at the big cancer institutions, as we know that tonsillar cancers can have a primary as small as 2mm (not cm), and move directly south into the cervical nodes without producing an oral lesion that is visible in early stages. It was only after a Hopkins study which did prophylactic tonsillectomies on all these people with positive nodes but occult oral environments, that we discovered this.

The lymphoid tissues on the base of the tongue and in the tonsil are different than other areas of the mouth that have an cellular architecture which consists of; a basement membrane, basal cells, (which is where all cancers start), and then layers of epithelium all the way to the surface. Tobacco carcinogenisis has always produced visible lesions because of the normal cell growth patterns from basal to upper epi cells. With no basement membrane, a really small primary can spin off daughter cells into the normal lymph drainage pathways from the tonsils, and directly into the nodes, making the process of metastasis much faster, and leaving the oral environment occult of visible lesions until very late development. These used to be called unknown primaries, because even a CT scan might miss them, and there was nothing on the surface to see.