If i was given to much radiation and has life threatening medical problems what can i do

I had radiation for a thyroid problem and was given a dose that was ver high 28 days later . i now have tumors ,graves,restaging neck carcanoma . i have been told the excess radiation has caused the many health issues that have been occuring for the past eight years.i just had a pap test and now it is showind cancer and am going in to have biopsy done on thursday.radiologist told me a couple years ago it is from the radiation.