I need advice on what to do here with her...?

Ok let me break it down: There is this girl I have liked for quite awhile now, but I just dont know what to do to get her. I am 17 years old and I have never been on a date in my life. We used to talk all the time (admittedly I start the conversations about 80% of the time) , but lately (since about a day after we went to a swimming party together, which was about 4-5 days ago) she has been just not responding to any sort of communication from me whatsoever. I know shes been getting at least some of the things Ive been sending her and shes not replying... What could be going on? What should I do? I really care about her and have strong feelings for her and I know that sometimes I may come across as clingy... but what honestly should I do here (if anything)? Because this may or may not be my social paranoia kicking in, but I just am worried...