I developed nodulo cystic acne in my mid 20s. I would have a continual 1-3 cysts, usually on my face along or under my lower jaw. On the advice of physicians, dermatologists, and the internet, I tried washes, topical antibiotics, benzoyl peroxide, oral antibiotics, more bathing, and less bathing. None of these made more than a minor difference. I never tried accutane; I was afraid.
My first big break came when I started making dietary modifications for one month at a time. I am reasonably fit, eat minimal processed food and not that much sugar. So, I figured that if there was a dietary cause, the solution would be a small change. I tried many things without much success, and then I stopped drinking milk. The effect was almost immediate. Before, I would go to work feeling oil ooze from my freshly washed face; that feeling disappeared within days. While my acne didn't go away, it was reduced by probably 80%. Severe acne went from being routine to an occasional annoyance.
The second big break came from a new physician friend. The friend recommended twice weekly bleach baths. Add 1/4 C of bleach to a warm bath, soak for a while, rinse the bleach off, and then rehydrate your skin with good lotion. I started doing this almost a year ago. Since then, I've had only 1 cyst, and it was at the site of a previous infection. The only downside is that you sometimes smell like you've been to the pool. Also, bleach is cheap.
It took me a decade to get to this point. I hope you find your solution sooner. Good luck.