My tummy is firm and later today it wasn't

Okay so it sounds like you're talking about your tummy feeling bloated, and then maybe it went down later. That happens to literally everyone, and it's super normal. Sometimes it just means you ate something big, or drank a lot of water, or even ate something your body isn't super into, like certain veggies that make you gassy.

Your body changes all the time, and how your tummy feels can be part of that. Like, for me, my tummy sometimes feels firmer or a little puffier right before my period, and then it goes back to normal after. Hormones can totally mess with how your body holds water and digests food, so your tummy can feel different from one day to the next, or even just within a few hours!

If it's just feeling a little firmer and then softer, that's usually nothing to worry about. But if you have really bad pain with it, or it happens all the time and really bothers you, it's always a good idea to chat with a trusted grown-up or a doctor. They can help you figure out if there's anything else going on.