Baby Vomiting or spit up?

Ok, my daughter is 7 months old. She has always spit up, sometimes worse than others, but we have basically got it all under control now. Tonight though, she "spit up" like normal, just a little bit, and it smelled like vomit? It normally smells like formula, or whatever food she ate, or whatever, but this time it smelled like that gross vomit-y smell. Just curious if sometimes spit up smells like vomit and I haven't noticed it? I don't know. She hasn't been sick or anything, her head feels a LITTLE bit hot, but it might be my imagination. She hasn't acted any differently or anything.

My daughter use to do that every now and then out of no where...she was never sick, and it never lasted long. So I have no clue. I just use to keep a closer eye on her those days.

How long was it before she ate? If it had been a while and her stomach had a chance to start digesting before she started feeling gassy, it would come up (i.e. spit up) but it would smell like vomit.

When babies/kids vomit when they're sick, it's always a very large volume. So, I wouldn't worry unless this is the case