Agree with above.
I guess the possibilities are mostly things like doing a research year, trying to extend med school (if you haven't graduated yet) and do something like a MPH or MBA (I think that you are/were already doing an MPH?). The major thing is to look like you are doing something, and really try to do something, that will be helpful you you in getting a residency match next year. There are a ton of specialties that are decent that are much, much easier to get into than derm, and I think if you were a decent enough applicant to get derm interviews then you will for sure be able to get interview in other specialties, if you try for them. If you still want to apply for derm then I would definitely, definitely have a backup plan, such as dual applying to derm + pathology, or derm plus categorical IM. At the worst you can just apply to a ton of medicine prelim years (to be really sure that you get one) and rank these at the bottom of your primary list so that you would/will definitely get an intern year even if you fell through the derm match again. That is what I would do. IM intern year sucks but IM itself doesn't really suck long term, because it has a lot of potential to do different things...I mean, one can pick a traditional specialty or hospitalist or primary care, or you can switch later to other things like occupational med, or urgent care stuff, or maybe even stuff like working in a vein clinic or as an internist who does a lot of spa type treatments or some skin treatments. Some IM internships are also quite a bit easier than others, and so if you don't want to get reamed there are some pretty cushy programs that you could pick and probably get into.