Im busy going through it now mate. Broke up from my wife in January and she has my 10 month old daughter. It came out of the blue too, I thought I was doing okay, odd days I felt a bit down, I developed a bit of a nervous twitch but I never realised what was up. If anything I was too hyper, always playing practical jokes etc.
One day at work a Tanker Driver did something he shouldnt have and I just went totally ballistic, started throwing things around, screaming and swearing at him. My mam told me to go see a Doctor, I did, and he related loads of things to me being stressed and depressed. Everything from a rash I had to my mood swings and twitch. I certainly dont fully understand it, and I know for definate that not many people do understand it. Too many people are too quick to say 'Snap Out Of It' and its just not that easy.
I refused medication as I really dont take pills (not even asprin). But I have started exercising, cut back the booze (a little), may go to counselling and even might try Yoga as the Doc thinks that will help, so hopefully I will get better without anti depressants.
I was put on the sick for two weeks and I was done in, it didnt help at all. I just felt that because I wasnt at work there was no need to get out of bed and no need to refrain from drinking, so after the two weeks was up I returned to work. To be honest, my gaffer is great, she always asks how I am and tries her best to keep my workload and hours sensible.
Oh and the Tanker Driver stays well out of my way too, he really thinks I was going to kill him!!
Hope you get it sorted mate, its not always easy to understand why you are depressed, you just know you are. I respect anyone who doesnt just wallow in self pity and gets themselves help, sod everyone who wants to attach stigma to depression, its an illness that 1 in 10 men suffer from at some point in their lives.
Good luck fella