Low moon alchohol induced, chemical or due to circumstances?

I have been feeling a bit down on an evening lately. I have been like this a few times so I have drank alcohol on an evening to cheer me up. However as it makes you feel more depressed the following day I stopped drinking 4 days ago as I did feel pretty low and was scared by it as I had not felt this rubbish in a long time. However in the last four days my mood on an evening has not lifted and I would have thought the alcohol withdrawl affects would have gone by now. On a morning I usually feel fine. I am fine if I go out and do something whether day or night. The problem is I do not have a lot of motivation to do anything in the first place. I am tired quite a lot of the time. I recently passed by university degree (10th September) after a very hard struggle and two resits, and now the only thing I have to is look for jobs. I miss not having a specific goal and feel insecure now not knowing where I will be working or what I will be doing in a year from now. I am seeing someone at my old university every week to help me with my application forms and I have started to get job interviews for my chosen career, but after all that hard work I just don't feel so exited any more, but know I need to find work as soon as possible because I am feeling very fed up. I recently did have a lot of celebrations and parties and lately things have been quiet and I have just felt bored with everything. That is why I was drinking.