How Can Depression, Mood Swings With Paranoia Be Treated?

I think im depressed and need help of some sort. I first noticed it nearly two years ago, i went through fases of ups and downs (about 3-7 months each). i didnt think much of it and my mum said it was just mood swings, but the depression dont seem to go away and each time it seems to be getting more frequent (it can sometimes now be within a day)(wake up feeling happy or normal and by dinner time i can be sicidle) and more extreem. I feel paranoid alot and trapped. when im not depressed i either feel empty and emotionless (i cant smile or cry) or i feel really hypo and ivincible and have more energy than i do usally. im not sure if its a normal thing but could you please help me out?...