depression?

i felt really down a few weeks before....but now i'm fine again....is this supposed to happen?

i felt like nothing was right and wanted to die right there and then.....is depression a random thing or is it builted up by many different reasons....?

it's like i wanted to die but afraid of losing some people....then i don't feel like doing anything at all....i really want to burst out and yell....i want to let go of all the stress i have....

does anybody have any suggestion at all?....where can i go to relieve my stress but at the same time it won't show out that ur trying to let everything out?....to keep everything to urself and release it silently where no one would notice?......any suggestions? any ideas? -_-''''