I Have Been Having Anxiety And Stress For A Few

I have been having anxiety and stress for a few months now. My heart rate would go up and it scared me and with having OCD I kept checking it which is not a good idea. I also have a low thyroid and I went back on 50mg of synthroid because I read that anxiety could be related to thyroid problems. I have been taking my thyroid med for 3 days and I have noticed that I have been having some palpitations. Not sure if it is my anxiety or the synthroid causing it.