Help !!! Why would a guy like a picture and then unlike it off of Instagram?

I told my crush that I liked him and he said " I don't know what to say , I wasn't expecting it all." After that happened he didn't bother to reply back , but for his birthday I sent him a message wishing him a happy birthday and he replied back with " Thank you Steph , I appreciate it 😁." I then called him out on how things got awkward and I wanted them to go back to normal. I saw him a week later and ended up giving me a hug. Last night I posted a picture on Instagram and he liked it , but a couple minutes later he unliked it. He likes other girls pictures except mine. I've had a crush on him since 7th grade and now we're in 11th grade. In middle school we used to talk and someone once told me he had a crush on me , but he never did anything about it. For example of I didn't say hi then he wouldn't say hi. It's like if one doesn't start something first than the other one doesn't. I'm really confused and I don't know what to do?
Help !!! Why would a guy like a picture and then unlike it off of Instagram?
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