I had to take a radiation pill for thyroid cancer. i feel like my taste has changed? things don't taste the same! will my taste return to normal?

Possibly.: Often with cancer and its therapy things like taste change. You have or have had something in your body that has or had a deep effect on it in thyroid cancer. Your therapy is done to destroy the acncer cells wherever they are in your body. So it may come back if the cancer is gone or be more persistent if you need ongoing therapy. If this is so, see your doctor for a potential remedy for it.

Most likely: Radioactive iodine treatment can affect the salivary glands and reduce the production of saliva. This is usually transient, but may take long time, depending on dose of radioactive iodine.

131 Iodine is likely: The isotope used, both for treatment of cancer and hyperthyroidism. The thyroid incorporates iodine to make thyroxine (t3, t4) physiologically. It's half life is 8 days. Effects and adverse effects will tail off after multiple half lives. It is secreted in blood, sweat, urine. So, you may be tasting iodine, or transient dry mouth from salivary excretion. Always check with your doctor.