Is my IUD coming out?

So I have had the Mirena going on 3 years. Starting yesterday I started having uncomfortable pain in my abdomen. I figured it might be cramping as I just started having periods on the Mirena again. I checked my iud and felt only one of the strings and it did seem much shorter. Now, naturally, I’m freaking out that my IUD is going to kill me. Since I can feel the strings I’m not sure if it is in place and I’m just period cramping or if it is moving. Should I go to the DR or am I just being crazy?