The alcohol was probably having an impact on your immunity, especially if you weren’t eating properly and felt stressed or depressed. Many kinds are oestrogenic and the impact on the liver and gut flora creates a good environment for yeasts. If you’re still getting symptoms, you might benefit from the anti-fungals and probiotics recommended here. Coconut oil is good for a lot of things. You’ll definitely benefit from removing processed foods and other junk from your diet and focusing on nutrient-dense wholefoods, but if you digest food well, it’s really up to you if you want to do the strict diet or not. People avoid things like butter that has 0.014g of sugar per tablespoon. I wouldn’t go through the cleanse/fasting unless your liver is in top shape. The best thing to do is experiment and not make any assumptions. This is all my opinion of course.
As for the depression, do you get any other symptoms at all? Any pain, acne, hair loss, cold intolerance etc? I’ve come to think of some forms of depression as hormonal imbalances. It’s unlikely you have a serotonin deficiency, so why isn’t it getting used effectively? Something is probably interfering. If you do want to boost your serotonin in the meantime, 5-HTP is available as a supplement, but if you can get to the bottom of your symptoms, you won’t need to supplement anything except tasty food 🙂
I’d look into stress coping, e.g. mindfulness, and exercise (no metabolism destroying cardio!) too. The effects that different kinds of foods and diets have on my mindset make me think getting all the biochemistry right is 90% of it though. It’s a shame people are made to feel mentally deranged by our ignorant culture just because they feel anxious or depressed. There’s so much more to it.