Silent treatment for 3 days??

Me and my ex recently started talking again. We’ve Getting along pretty good. He wanted to take me out for my birthday. Had the most amazing date you could have (no sex). He Even texted me saying how much he enjoyed it. Then when I saw him at work (I work with him) he was totally different..within a 5 hour time span of texting me. Now it’s been 3 days of him not even acknowledging me..it’s driving me crazy. How can you have an amazing day and then ghost me and treat me like nothing I don’t get it. This isn’t the first time he’s done this when he was mad, but I don’t think I gave him a reason to be mad. I texted him 3 times within 3 days to let him know that I want to talk and want him to tell me how he feels..not in a angry way at all. What should I do and what does this mean?