I'll try to keep this brief, so here's a generic summary: It could be a combination of those things or some outside factor that cleared you up.

First, Accutane is not an acne cure. It treats the symptoms, including some underlying causes of why people get acne in the first place (it doesn't treat chronic inflammation, just the formation of acne), but there is no guarantee it will work for you. With that said, two months isn't long enough to really see a difference, and some people take 4-6 months before they notice a change. I'm assuming you already know the drawbacks, risks, etc, so that's all I'm going to say here.

As for the festival part, I'll try to list off some possible reasons it cleared you up.

Fasting, not eating or drinking only juice, generally helps people clear up, and some find it helpful to repeat the process every so often. But you should *not* be afraid to eat, ever. Your body is specifically designed to absorb nutrients from the food you consume so that it can repair itself. You do not need supplements, vitamins, and so on, unless you have an actual deficiency--the only reason I mention that is to underline that you need to eat. Don't starve yourself because you think it may help with your acne. Consensus is, once you start eating it will all come back worse than before (body not used to the influx of insulin, hormones firing up, etc). From personal experience, not eating is a terrible idea.

Not washing and sweating helps to release toxins in your body and reform the acid mantle of your face. I've seen actual examples of people on these forums clearing up just by not washing their face for a month. It doesn't work for everyone so it's not a miracle cure (there could be other causes to your acne), but using harsh chemicals on the skin can irritate it and cause breakouts. Also, some people find that excessive sweating causes acne instead, so they avoid hot weather like the plague. Probably not so in your case, since you started clearing up.

Drinking booze and smoking, not so much. Paradoxically, I've read about people clearing up by just eating junk food and drinking beer. How that works is beyond me, but it's probably not very healthy for you in either case. Try to drink in moderation; if you can't drop smoking, also do it in moderation.

My suggestion to you would be to re-examine your diet and waste elimination. Start by thinking back to your bathroom going habits. Are you: constipated, bloated, infrequently visiting the bathroom OR bloated, gassy, having loose stools OR having liquid stools, discolored stools, or getting diarrhea from some foods (all possible symptoms of IBS, a very common condition)? If any of those sound familiar, you probably have stomach digestion problems and that's leading to inflammation and possibly acne. Ideally you should go to the bathroom about twice a day with no discomfort or straining. There is more you can read about that if you have the time, and from my own experience it is important to really focus on this part to treat yourself, should you have the symptoms.

Diet itself is tricky because there is not a single diet that will help everyone--the trick is to find something that does not cause inflammation and heals your gut instead. Some do fruit-only and that can be absolutely crushing if you struggle with sugar sensitivity. Paleo can lead to constipation in many, or gas due to the vegetables (and both can lead to inflammation, ha). I guess the best advice I can give is to try to eliminate certain foods that are thought to promote acne to see if that helps: milk, sugar/snacks/soda/etc, gluten (bread,what,rye,etc), soy, red meat (eat chicken/fish instead), vegetable oils (extra virgin olive oil is alright), fruit, and a few misc things. Seeing a change with this can take 2 weeks to 2-3 months. If I can recommend one diet that sort of eliminates all that stuff while giving you a list of foods to eat, try the low FODMAPS diet. It's not super restrictive, but eh, that's what I eat right now, more or less. On that note, acne in the chin/mouth area only is actually associated with digestion issues. That might be why you're only now struggling with it for five months instead of five years (my assumption).

As a sort of side note, avoid taking antibiotics for any extended period of time. Doing so absolutely destroyed my digestion and immune system, and gave me other problems, and I am not the only one. Acne is always worse after you stop.