Body twitches when boyfriend touches abdominal?

Ok it's not like a sexual touching he does, it's like when someone lightly touches you, and you feel ticklish. That's how I feel but worse. He would swiftly touch around the right of my abdominal below my bellybutton, and I would have this irritating twitch around there/and sometimes all over my body. It would feel good but at the same time it would hurt like hell cause I would twitch real badly. I don't know what it means. Also when I do it, it doesn't happen, but when someone else does it, it starts happening. It would also happen when I do an exam and when the doctor checks the stomach to see if your constipated and all, and I try not to twitch, but at the end it just hurts. Does anyone know what I'm talking about? What does it mean? What's it called I look all over the internet, and it doesn't say anything about it. How can I fix it? I always feel weirded out by people going near my bellybutton/abdominal because of this. Can someone help? Thank You.