Unilateral tonsillar enlargement. I be?

I was diagnosed with invasive breast cancer in 2006, underwent several cycles of dose-dense chemo with both Adriamycin and Cytoxan. Over the past year or so, I've started having periodic trouble swallowing and a weird, pressure-like sensation in my throat, along with some hoarseness. I've also started to drop weight unintentionally, about 17 lbs now. I've also been unusually tired and have had periodic night sweats and itchy skin all over despite moisturizing. My tumor markers have always been steady since right after chemo finished, staying right around 19 or so. The past 2 checks, they're now at just inside the high end of normal. CT scan shows I have unilateral tonsillar and base of tongue enlargement on the left side, along with 'punctate calcifications of the tonsillar fossa', and several enlarged lymph nodes. What could it be and how worried should I be? Thank you.