I (25F) am struggling with people treating me/acting different

This is a struggle I have been experiencing at work. I understand that work is usually an environment that people see as nothing more than just a job, however, the majority of us are all super friendly with one another, even outside of work. We poke fun, joke around, and have a great time. It’s something that I normally look forward to, since it’s all I have going for me in my life at the moment (not good; I know), but now it has become something I dread. I’m biting my nails over seeing who I work with, and anticipating whether or not people are going to treat me like their friend or like their enemy. Now despite the fact that we’ve all had our moments, only a few, we have all managed to talk it out like mature adults, and move on with our lives as normal. However, within these past couple of months, I’ve noticed changes in peoples behavior. To my knowledge, I haven’t changed a single thing about me. The only thing different is that I’ve learned to not care about certain things too much, like when people are upset or treating me poorly, in order to keep myself from becoming angry. Sometimes it just becomes too much though. Anyways, people at work who’d I consider my friends have become different. They treat me as if I’ve wronged them in some way, even though I only interacted with them just yesterday at work, and everything was great then. They don’t look at me, don’t joke around with me, hardly talk to me at all, and I don’t know why. Even a guy who came back from college to work the summer is doing it, and I haven’t spoke to him for 5 months; leaving on good terms as well. He even treats all the new people better. It hurts my feelings honestly. I inquire about it, and they just tell me that nothing is different, which makes me feel like I’m going crazy. These coworkers treat everybody else the exact same, but brush me off, are distant, cold, don’t make an effort with me, and treat me poorly even when I’m still just trying to be happy and nice to them. I don’t know what I did wrong, and I can’t keep working like this. There is one common factor I’ve noticed, and it’s a specific person I work with. They follow her around like puppies, always treat her with the same jovial attitudes, have fun, etc. Then when I come around, it’s like I ruined the party. Even she herself is guilty of treating me these ways, and she was my best friend. I now know this was a mistake, but we’ve told each other all kinds of things, traveled together, and even have one of those friendships that make people question our relationship. However, I get this weird feeling that she could be the cause, but I just don’t know why she’d do that. Every person I have issues with is somebody she craves attention from, and gets in the way of me being around. I’ve confronted her about this, and she explained that nothing bad is going on in her personal life, she hasn’t been acting different, she hasn’t noticed anybody else acting different, and sometimes she just doesn’t pay any mind to people not in her work zone…which is a lie. She confronted me about talking to a mutual friend about how I feel like she’s talking shit behind my back, to which she said hurt her feelings because she’d never do that. But yeah. I’m no stranger to the fact that not every single day is going to be a good one, not every person is going to be happy that day, everybody has stuff going on, etc. BUT…they never act any different…around anybody who isn’t me. What do I do???