If anyone is out there please help me with this problem:'(?

So ,here I am , having this problem for 3 years now. Well my name is Daniel and ever since I went to my secondary school , my life in year 6 I moved house and I went to a new secondary school. I was the perfect kid and that's what I missed so much. I had the looks I was the class clown, popular, good at sport and I was clever. So I went to my new school with 2 other people from my school they were good mates of mine. Ever since I came to this school , I lost everything. I went bad at sports, I'm not popular anymore and I can't talk to girls everytime I talk to girls I crack up and don't know what to say. This year it's gone worse, the only thing I have now is my intelligence. I'm quite popular but that's all, I feel depressed I keep having flashbacks of my childhood , I'm crying as I type this. I feel so alone and I want to have my childhood back. PLEASE SOMEONE TELL ME WHAT'S HAPPENING? even my mates say I've changed for the worse, they say I've gone quiet and I was so loud in primary. CAN SOMEONE ALSO TELL ME HOW TO RECOVER FROM THIS?