Boyfriend of 4 years isn’t reading or responding to my messages

I just got back Sunday afternoon from a trip I took with my boyfriend (of 4 years) and his family. It was a short trip. We got into a fight on Saturday but made up that same day. Since then he has been a little different with me. He isn’t reading my messages and he is responding to me text messages. He called me yesterday and told me he had gone to a dentist appointment and he was going to nap because he was feeling out of it. His sister told me he was up and talking to her and his mom and that he went to go eat himself. I texted him twice yesterday and haven’t heard back. He always texts me goodnight and good morning. Haven’t heard a word sine that last phone call. He isn’t opening my messages either which is strange because he was up according to his sister and he always has his phone nearby. She said he wasn’t feeling all to great as he had some work done at the dentist but seemed fine enough to eat and talk. I’m confused. I don’t really understand what’s happening. Is he avoiding me? Did he say he was passed the fight but really wasn’t? Does he just want space and isn’t telling me? I feel lost. I don’t want to bother him because if it’s space he’s looking for I’m trying to be respectful of it but he didn’t communicate that to me at all. I thought we were ok. Now I’m just confused and anxious…