Cliques

So I was at a singing event and there are these girls who hang out are that are kind of nice to me. But I do a lot for them and give them gifts,tickets, and advice. Today they saw me sitting alone and didn't invite me to sit with them and they took pictures right in front of me and didn't even bother to invite me in. Even one girl every time I said something to her like she just looked over at me. But I don't suck up to them or anything I just plain do nice things. Some of them are going to high school with me but I just don't know how to go about the situation.