I need advice on a guy!! PLEASE HELP

Hi ladies! So I’m 17 and I’ve been talking to this guy for almost a month now.. I found him through mutual friends and DMed him on Instagram asking for his snapchat and we have been talking ever since. Let me just say that goes to a different school and we haven’t met in person yet. We only talk through snapchat but like not on the chat part (we send pictures) so we have been talking for a little while and all the sudden out of no where he sent me a mirror picture of him shirtless and with his towel hanging low to see his v line. He never sent me any kind of picture like this before so I didn’t know how to react. I wasn’t upset that he sent it to me, he has a really nice body but I just didn’t know how to respond back. I knew he was doing it for attention so all I did was send a picture of me like with a soft smile. He just started sending back normal pictures after that and so I didn’t really think anything of it. He already knows I think he’s attractive because I told him a few times before, but i am now feeling like I should’ve been more flirty or gave him a compliment after he sent me the picture. Yesterday (the day after he sent the pic) he sent me like 3 Snapchats during school ( he usually Snapchats me every morning but I feel like he just sends it to all the people he has streaks with) but I responded after schoo asking how his day was and he answerd and I responded and he left me on open. And now today he sent me a snapchat this morning and I responded and he left me on open without responding at all. Do you think he stopped talking to me because he was embarrassed about the picture he sent or like because he didn’t get the reaction he wanted from me? Or maybe because I didn’t send a picture back? (I’m not the type of person to send nudes) Or am I totally over reacting?

Thanks for whoever took the time to read this(: