Can any mental health professionals (or just anyone) tell me what's wrong?

-for the past like 2 years I've been feeling really low in myself every now and then thinking I've no friends and no one to turn to

-This feeling has gotten more frequent in the past 9 months maybe?

-I feel like I can't go anywhere without a friend because people will judge me and call me a loner

-I feel like my friends don't like me and get reeeallly upset when I'm not invited out/they can't do my plans even though I know they don't do it consciously

-When I do get invited by a person in a group invites me out, I don't go even though I want to because I feel like no one else in the group likes me (even though in my head I know it's not true but I can't stop thinking it) (this senario happened today)

-I feel like I can't do certain activities e.g. Cycling, or running or something because I'll be judged

-Often get really low for no reason

-Soften have really good days but then it all crashes down and I feel horrible for no reason all of a sudden

-I feel like all the people I would call my 'closest friends' wouldn't say the same about me and it makes me feel horrible

-cry and overreact at the tiniest things