Okay, I need help it's about my heart!?

So the other night me and my boyfriend where laying on his couch. He was writing words on my stomach up near my kidney. I'm ticklish and all of a sudden my heart starts beating irregularly. It was beating really fast. Now I don't know if it was from him or just because but it hurt really bad. I just want to know if anyone knows what might be happening. And tonight it's still hurting and it's hurt all day. Thanks in advance. :)