I need advice please (SH)

I, 14m has just started cutting a few days ago. I have never been diagnosed with depression but sometimes I get in my head and start to have thoughts but a few days ago before I knew what I was doing I was cutting my upper arm. I haven't cut anywhere else beside my chest. I'm sorry for posting this but I felt like I needed to get this off my chest before I did something stupid so any advice is appreciated.