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I can understand why you feel that way about your parents and going to the doctor, but in reality I think they were only doing that because they wanted to help you. Your parents probably don't understand much when it comes to self harm and wanted to make sure that you were TRULY okay, and some of the things you mentioned such as the doctors making you put on that type of clothing were probably just them following their protocol.

I know you said that you aren't comfortable talking to them about it, but you can at least tell them what really won't help you, such as taking away your phone. My parents took my phone away for a while, but you can explain to them that nobody talked you into this or anything, but the people you talk to on your phone can give you support. Maybe print out pamphlets on self harm to get them to understand.

Now that your parents know, though, I think you should get support from someone since as a guidance counselor or professional. Since your parents know about your self harm, they should be able to keep everything you say to them confidential, and it can be really beneficial. They won't be there to judge you.

Try and find ways to express your emotions though. Writing, art, music, and exercise are all really good ways to do this, because you are releasing what is pent up inside.

Also try and find ways to make new friends, either online or even in person. You can join clubs, social groups, and sports teams for instance. Not everyone will backstab you.

Self harm won't really be useful, though. As you can tell now, it actually does create some problems for you, even if the injuries aren't deep. I really do advise trying to find another coping mechanism.