Hello, My 66 Year Oldd Boyfriend Had Basal Cell Carcinoma

Hello, my 66 year oldd boyfriend had basal cell carcinoma removed in June, came back all clear! Since that time he has noticed a lump and continual swelling of the side of neck, he requested a cat scan and it has taken over a week for results, meantime he woke up this morning with a stiff neck and a significant increase in the size of the side of his neck!!!! Any advise of what the possibilities of what this could be???!!