Friends keep leaving me out!! Help?

[Floppy]

I have a large group of "friends" but lately many of them have been leaving me out. Last week I was supposed to be go shopping with friend "A" but friend "A" and my other friend (friend "B") went without me and made it obvious that they were leaving me as they put up lots of pictures on social media. Friend B thinks that she's what keeps the group together but I'm honestly sick of it. I'm also friends with this boy who friend A keeps on walking home with and leaving me to walk by myself. All my other friends love friend B but I just think she is so full of herself and thinks everyone loves her!! What should I do??? I don't know wether to just act normal and deal with it or wether to bring it up?