Why are they ignoring me? i am just really confused and need help.?

I have two friends that are one year older than me. Im a freshmen.. they used to love me and wanna hangout with me. i became very close with one of them ( carrie) and kinda the other one (sarah). they used to wanna hangout iwth me all the time and stuff and now sarah got into this sophmore group who shes obsessed with. they think they are sooo cool and its soo annoying. i can tell they walk all over me and only talk to me when they need somrething. but when i need something they dont answwer. i ask them why dont we hangout anymore and they are just like idkkk and mumble ****. waht do i do? i did nothing wrong...