Sore lymph node then sore throat for a wk, no flu symptoms. then sudden 8lb gain in 2 mos, w migraines > 1x per mo, no period for 3 mos, not pregnant.

Check for thyroid dz: That's an interesting history. The first part sounds like a viral infection. It may have affected your thyroid gland. Menstrual irregularities are common in thyroid disease. The weight gain suggests and underactive thyroid. I would begin with confirm you are not pregnant and testing your thyroid stimulating hormone level (TSH).