Hey Mark,
I think the reason why Nystatin is being discontinued on amazon - and why I had to get it from Germany – is that it’s sort of an old school medical remedy. My dermatologist who recommended it in the first place was sort of old, so I wouldn’t be surprised if he practiced old school medicine.
I went to my regular doctor’s the other day, and he told me that he didn’t really believe in nystatin despite my success, and he defended the standard treatment using the mixed formula of hydrocortisone and antifungal ingredients and an antifungal shampoo. I expressed my concern about the hydrocortisone because it makes the skin thinner and more sensitive in the long run. And then we sort of came to a middle ground.
The hydrocortisone is not really essential to the treatment of SD, since we just want to go after the fungus. Yet, it is the hydrocortisone component - not the antifungal - that limits the use of the formulation and restricts us to only something like one or two weeks of continued use. My experience with a remedy like these, e.g. Brentacort which I was prescribed, is that it works wonders as long as you use it, but within weeks you’re in remission with SD all over your face again.
My doctor is not very fond of nystatin, though, for some reason that I didn’t really understand, but hey, I don’t have a medical degree (keep that in mind ;)). So he basically suggested another antifungal, I guess a newer, modern formulation, that doesn’t contain the hydrocortisone and that you can apply for extended periods of time. He suggested Brentan, which is over the counter here in Denmark and contains miconazole, a type of antifungal in the same “familiy” as the one in my shampoo (climbazole). I haven’t had any experience with this or other pure antifungals, but I like the idea. Nystatin is probably not a miracle drug, but the miracle effect is that you can use it for a long time and really get rid of the SD and allow your skin enough time to heal and regain a strong barrier and balance. Maybe you can get this effect from other antifungals just as long as they don’t also contain hydrocortisone so that you’re limited to 1-2 weeks.
Of course, don’t take my advice for medical facts, but as inspiration. Talk to your doctor about hydrocortisone-free alternatives. Get his opinion on nystatin, or perhaps another antifungal. Maybe Brentan?
Nystatin worked for me and I’m very happy that I did, so if you cant get it where you are, try other antifungals and if they don’t work, then you can go through the hassle of acquiring nystatin, but for all I know it’s not necessarily the only option. I just finished my last tube of nystatin, but next winter I’m thinking of trying Brentan instead, if I get into trouble. It would be interesting to see if there’s a difference 
As always, best of luck!
Stay healthy.
Hopefully one of these links work. Difficult trying to order when its in Danish or German!