Difficulties with relationships

Hi,

I'm sorry for putting this thread here but I didn't know where else to put it. Some things have recently come to a head which are really causing me a great deal of worry and to be honest I'm frightened.

Recently I made a new friend through work, someone I'd been interested in getting to know for a while. Anyway, things were going along swimmingly and we'd grown rather close, until the other day when we went out for a walk together. I noticed she seemed a bit less interested than she had been previously and afterwards she said she'd had a nice time. All of a sudden I've found myself desperately wanting to run away from the situation and overanalysing every word, she texted me yesterday and it took all of my willpower to not text her back and tell her to leave me alone. Logically I'm not sure I can see what she's done wrong, but I just have this intense emotional response of wanting her to leave me be.

I bring this up because it's a pattern in my relationships, most of my friends are kept at arms-length, which feels okay to me, and I dip in and out of them when I can. The romantic relationships I've had have pretty much all ended with either me pushing people away when paranoid thoughts start or the other person getting sick of distance I start putting between myself and them. And when I get rejected I find it very hard to deal with.

I've noticed that, as relates to this new friend, I've started having paranoid thoughts, like she is joking about me with work colleagues behind my back.

Just to add some extra context, I've had bouts of depression in the past, self-harm and also bulimia. And I experience very disconcerting highs and lows, at times I feel great, then all of a sudden my self-esteem seems shot and I feel like I don't know who I am anymore. I feel almost like there's no anchor holding me down, nothing I can really identify as myself.

I plan on getting a GP appointment but I just needed to ask about it, because I'm starting to get very worried.