Why does coworker give mixed signal?

Have this girl I used to work with I guess we don't get along now, I don't know one day she's telling people she likes me I catch her staring at my junk the next she's bad-mouthing me and avoiding me in the next day, then she's talking to my coworkers and telling me she has acid reflux too like me

Why does coworker give mixed signal?
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