Trip to the ER

Last night my mom took me to the ER because I put my back out really bad. When they came in to give me a shot the nurse said "I cannot give this shot to you because my system says your pregnant." 1st of all NO ONE asked if I was pregnant 2nd I haven't been here since my tubal surgery in November 2015 so how the hell am I pregnant in your system! So, when I got home I told my ex which would be the ONLY guy, but I had a period since we had sex. This was his reaction...Was he hoping they were right?