I (15f) have recently been so worried lately of having skin cancer, particularly melanoma. It has got to the point where I am too scared to go to the GP because I am convinced that I have stage 4 cancer so I'm wondering if anyone here can share some advice.

I have a mole on my armpit which is about 3mm and is an oval shape with a slight blur on the top. The thing that scares me most is the varying shades, it is mainly brown with some black/dark brown clusters in it, maybe a tiny bit of red too and from the side it kind of looks like it has a dip in the middle. It looks like it is slightly scabbed but I think it does get irritated by my clothes sometimes, I have never seen it bleed heavily or ooze. It feels weird, hard when I press directly down but I can move it around and it feels more like a skin tag. I don't remember when I got this mole but it was definitely at least a few years ago and I don't think it has changed too much, at least not in shape maybe in colour. Over the last few days I have been obssesed with it and am constantly checking and measuring to make sure it hasn't changed. It scares me so much that I could literally have had melanoma for years now and not know it. 

I went to the doctor for something unrelated about a year ago and he said that my lymph nodes felt slightly swollen. However I couldn't feel anything and it worries me that a similar situation is happening now and that the cancer has at least spread to my lymph nodes. 

I have OCD/health anxiety so this fear has been really hard for me to get rid of, statistics usually help me but I always worry that I'm that one in a million person my age who dies of cancer.

I have no family history of skin cancer, although atypical moles do run in my family and my grandad had to get some removed because they looked suspicious. I never have used a tanning bed in my life, I previously got sunburned badly a few times, but it has never been near my armpit. I just worry that I have faulty genes or something and if I go the GP I will get a terminal diagnosis. I'm sorry if this sounds silly but I really need some advice from others who have been through similar things.

Thanks so much in advance!