Over the last couple of years I have noticed That I some time get depressed for no reason I can Think of and these spats of depression last from a couple of minutes to about a week (the longest to date) and If somebody could help me find the cause, I would be greatful. Also this depression has made my think about self harm and death on mutiple occaions (Note: this is my only true outlet and everybody else that I could talk to is squimish, don't understand or not there so I am left bottaled up with all the stuff I want to vent but can't because of the reasons I just gave)
There is a distinction between feeling depressed and being depressed. Feeling depressed is a mood which passes, while being depressed is when this feeling depressed becomes the default mood for a significant period of time. Like other mood changes, there's sometimes no reason, but there's often a cause to feeling depressed, like someone close to you has died or breaking your normal sleep pattern. If a week is the longest, you've ever felt depressed for, it's not really an issue. Having a really bad week for no real reason isn't uncommon.
Get some common sense, and see a fucking therapist. No, I am not serious. I am just doing exactly what you did here to someone else. It's not fun is it, to look for help and just get asshole comments instead? Anyways, I just think you're experiencing is completely normal. Mood swings happen to everyone. Especially during your age. However, to make sure I would still try and get some help. Suicidal thoughts are not something to just shrug off.