How do I apologize to my boyfriend ’18M’for something | ’18F’ don’t know what I did, and make it up to him?

My boyfriend '18M' and I '18F' are in a good relationship or so I thought. He wasn't texting me yesterday claiming he was tired and I get it he is sick. It normal to not feel yourself when sick, but he was active on his socials.i asked why if he was tired all day, why was he active. He didn't deny it, he just said he was active, and then he said he was disappointed in me and upset with me, I don't know what I did. I tried talking it out and saying I was sorry even if I didn't know what I did, he said I shouldn't be sorry bc I already did it. But I kept apologizing either way, and telling him I love him. I told him we could talk about it tmr if you didn't want yesterday but he said no. He said everything will be okay tmr, aka today. But he's been dry and i don't know what to do. I'm thinking of going to his house to talk about it? I really did try talking it out. I told him I love you and he said" I'm sure you do" what does that mean??? Does he think I was unloyal to him??? Which I wasn't, I haven't even talk to no one these 2 weeks!!!'ve always been loyal to him, I love him so much! What can I do to make him feel better?? What should I say?? I want outside advice?? I plan to go to his house to talk about it, but what if he ignores me, or if I bring it up he changes the topic? He said I already done this thing many times?? But what have I done ?? I just want to be better for him.please give advice and how to apologize to him better or how to talk it out ???