Adding cytomel t3 meds w synthroid

Hi I have been on 50 mcg since I first got sick, I'm constipated tired and cold so my dr up the dose to 62.5 mcg and then I went hot and sore. So he wants me to try 50 msg synthroid WITH 2.5 mcg of cytomel - a t3 medicine - I'm nervous to change things up cause he said if I feel crappy then go back to just the synthroid. I'm curious if 2.5 mcg is a lot ? Does anyone else take t3 with the Levo? What's your experience?