I Had Iodine Treatment Last October Because I Had 2

I had iodine treatment last October because I had 2 nodules from hyperthyroidism. The treatment did kill 1 and the other reduced in size. My last TSH reading 5.83 and T3 T4 readings was in normal range so my endo took me off synthroid I was taking for few weeks. Because I was having a lot of symptoms like heart palpitations irregular heartbeats because I was taking levothyroxine for about 2 mo then recently switched to synthroid a couple weeks ago prescribed by hospital and primary doctor but my endo says I'm fine that I don't need it because my levels are not outrageous What do you think