Sure - it can be a side effect. You should start or now be - hypothyroid. This can be a symptom of either hyper or hypo even if RAI is not done.
How are you feeling otherwise? Have you had your blood tested and what is your results? What dosage of meds are you on and for how long?
I am feeling much better, the doctor give to me some med for the hyper go down fast after RAI, because this was still high after I done it. I will be taken it for three weeks decresing gradually,hopeffuly i wont go down to much, I am afraid to became hypo and gain weight.(is that inevitable?) Thanks for your atention!