How old is your lo? Is his development on track? I’m sure it’s nothing, so I don’t want to worry you, but infantile spasms can sometimes present with “jack-knifing”, where they bend at the waist forward. But kids with IS are usually developmentally not on track. I’m only telling you this b/c one mom had a baby who did this, and it was said to be Sandifer’s, when it wasn’t. If you’re at all unsure, then videotape it and show your doctor. It’s probably nothing, but I always think better safe than sorry.