I Was Diagnosed With Thyroid Cancer In October 2013, With

I was diagnosed with thyroid cancer in October 2013, with Thyroidectomy and central neck dissection in November 2013. The following February (2014) I had RAI treatment. Then in April of this year, I started displaying antibodies in my blood work so doctor order a tracer dose of RAI...Last year after my full dose of RAI my periods stopped for a few months, but finally got back to normal. Once again, after this tracer dose I am experiencing the same thing. Is this normal?