Friends

So basically,

(I have 6 friends.)

So it's september, i've just got back from summer holidays and suddenly 5 of my friends dont like talking with me, being with me or anything. I dont know what i have done to offend them as we were perfectly well off before. They always spam pictures of me on the groupchat and they always ignore me. Today in class they all got up and moved to the other desk, leaving me alone. In this situation i was happy for my 1 other friend as he understands me and sticks with me. In my opinion, they're all fake friends, that just look for attention out of things. They are dirty minded, dont care about their studies and always beg for attention in class. I just wanted to write this to get this off my mind, but the problem i am having is that i have these people in all of my classes, and sadly i dont have my 1 good friend in any of my classes. Also, its hard to change friendship groups as in year10, most people have cemented their friend groups and dont change them. I guess i just wanted to ask for advice on here. Thanks and sorry if what ive said is hard to understand.