Tenderness/pain in thyroid bed way past TT-this happen to anyone else?

Hi,
I had two surgeries in Nov 2010 to complete TT. I was diagnosed with papillary carcinoma-follicular variant. Cancer was encapsulated and very small. No lymph node involvement. In March 2011 I elected to do an ablation dose of radioactive iodine. Whole body scan was clear and thyroglobulin was very low. Saw the doctor again in July 2011 and all looked fine with blood work numbers. In August I started experiencing some other random symptoms and have since been diagnosed with lupus. Not surprised-had Hashimotos prior to TT and my brother was diagnosed with juvenile rheumatoid arthritis at 4yrs old.

Earlier this week, I experienced tenderness/slight pain in the thyroid bed area. Also, pain when swallowing and having to clear my throat. Lasted about 3-4 days. I spoke with my doctor's nurse and I am scheduled to have blood drawn this week with an appoint the last week of January. I detected a sense of urgency from the doctor.

Has this happened to any of you?
Could it be leftover thyroid tissue?
Can the thyroid regenerate?
Wouldn't the radioactive iodine ablate any remaining thyroid tissue?
I have not had a sonogram since prior to surgery-is this normal?
Could it be lymph node involvement?
I know my ANA antibody levels are up...thought it was the lupus-could thyroid cancer cause this to track up?

Thanks in advance for your feedback!
Marlo