Need a guys perspective, why did he lose interest and how to get it back?

How do I get him interested again and what went wrong? I've been casually dating someone for about six mounts. I haven't had sex with him yet. Were both pretty laid back and not very intimate (emotional wise). In the past he's been pursing me but recently he seams less interested; hasn't been talking to me, putting effort or trying to hang out. He hasn't been texting me, which is odd since we rarely go more then a day without talking and he's always the one to initiate the conversation. The change was pretty sudden and Im confused what turned him off or how to get him interested again. Lately he's been hitting me up to hook up more and I've been the one arranging our hang outs which have been pretty casual. The only reasons i can assumed that could have caused this is the fact i'm not into just hooking up, we haven't done anything exciting together recently, he perceived my asking to hang out as clingy, he's wrapped up with his friends right now or something he got to know about me turned him off (i can be somewhat insecure and ditzy but i try to hide it). What could have caused this and what are some good ways to gain his interest again? Sexy facebook pictures? Hang out with other guys? Ignore his texts (We communicate mostly over text but i'm not sure how to get his attention by doing this when he's rarely