Casually seeing someone

So I have been casually seeing someone for over a month now. We have hooked up a few times and enjoy spending time with one another. I was with him Friday night into Saturday morning, everything seemed to be fine. We were in contact a few times yesterday l during the day and in the night just seemed indifferent. He told me he was brooding which I quite didn’t know the meaning until i googled t. I sent him a text around 11 this am saying like I’m always here if you ever need to chat and such and got no response. I’m going crazy. What do I do!?