Thyroid cancer reoccurrence after 23 yrs.

I had one side of my thyroid removed and the other side was killed by idione ration back in 1989. On August 7, I fell off the roof and rushed to the ER. The CT scan showed broken bones but also a node in the base of right lung. A PET scan on August 30 confirmed a high uptake in right lung base and also in Hila and subcarinal lymph, followed by bone and brain scan a week later which were clear. A CT scan guided biopsy was performed on September 30 showed a papillary thyroid cancer in right lung. Now I am scheduled for I-131 scan for October 24.
I am coughing a bit but I have severe indigestive, not sure if it is related?