Had something like this happen to me during a summer tour program I went on when I was 15. A seated coach bus size of people, so like 50+ people. The guys would bully me, but we were stuck on a bus together for a month, not like I could ignore them.
Then everyone would be randomly nice to me. Like I would have a swarm of girls wanting to take pictures with me and being all seductive like. Next day, they would be assholes again. It was really confusing.
When I got home, I found out that they made a Facebook group dedicated to making fun of me and I was literally the only person on the tour not a member. Even the staff members were part of it. All those pictures they took with me were posted and they would make fun of me in the comments. They took a lot of pictures of me when I wasn't looking; like them sticking their bare ass cheeks on my face while I was sleeping. Every discussion was targeted at another one of my insecurities, like how my hair was thin, making me look like I had a bald spot." (I was only one year out of cancer at the time and my hair had not grown back well. They didn't know that though.) Then just a lot of screen shots of Instant Message conversations they had with me over AIM where they would dissect everything I said or set me up to say something and not show the full context. I stopped talking to them once I learned about the group.
It was pretty devastating at the time. I always felt like a loser, but I was always told it was in my head. It's one thing to be ignored, but these kids went out of there way to harass me. I must have been really weird. I have always been the quiet guy. Maybe I was just an easy target. This was in Facebook's early days, so I couldn't even get FaceBook to remove the group.
The worst was what it did to my confidence. The Facebook group represented tangible proof that confirmed my negative thoughts that I was a loser. Whenever I met new people, I would get anxious that they would see through my fake confidence and find out I was a loser. It took until college for me to get over that insecurity.