Need help IDing Evil Clown movie
 

Hey all,
I'm trying to find an evil clown story I remember seeing as a kid in the 90s. It may either be a movie or an episode of a TV show. I talked about it with a friend recently and he was interested in checking it out, but I couldn't remember the name, only a few scenes.

From what I remember, an evil clown goes to a kid's birthday party. That night, the kid spits up blood. The clown is supernatural and near the end, breaks into some kind of high-security building (maybe a police station?) but can't be seen on security cameras. What I remember most is the ending because it scared the crap out of me. The boy and his mom are having a picnic by a stream and the boy has his back turned. The kid turns around in slow motion and you see that he now has a clown face. I'm not sure how scary that is now, but back then it was super freaky.

Does anyone know what this was? I've searched ALOT on imdb and other sites and can't turn anything up. Would love to have some help, thanks!