Just friends

Urghhh not sure if I’m going into a manic phase for various reasons but I really also really like someone at work - now when I’m not manic I can just be friends with people, but when I feel like I’m starting to be manic seem to think who ever is really nice to me seem to fancy me and I then fancy them and I seem to be a bit obsessed (in crease social media presence on their thing etc) now it is clear this person does not fancy me then I just feel sadder knowing they don’t but at same time embarrassing myself. Does anyone else have this happen to them?