I will be having RAI next week for thyroid cancer. When my Dr.'s nurse was telling me about the treatment, she mentioned that there was a chance I would lose my sense of taste for awhile. She said it could happen a week to a few weeks after the treatment and is due to temporary inflammation of the salivary glands.
So, hang in there. It's only temporary.
You might try asking your Dr. if there is anything you can do that might help with the inflammation, so you can get your sense of taste back soon.