Laughing, feeling happy can give off the same response as if you were fearful. Doesn't seem fair, does it?
This has happened to me so many times. And when the seed is planted in the brain that anything joyful can turn into what seems a panic situation it tends to creep into anything you get pleasure from, like playing the piano. I play the piano too and had exactly the same thing.
The best thing you can do is not to avoid and carry on as if it's nothing, I know difficult because it's in the back of your mind. But take the feelings of being intense and not a threat. Once I did that the fear started to disappear.
Don't ruin your joy over a feeling or thought. x