Without a doubt, the easiest way to avoid a crash after the post-race high is to pick a new goal. Decide what you want to tackle next -- whether it's getting faster, going further, being more consistent with your training, trying complimentary workouts, or maybe even setting your sights on a different sport altogether -- and put a plan together for how you'll go about achieving it.
My clinical and research experience and reading of the literature convince me that medication is essential for most people with severe and chronic symptoms. It is equally clear that medication is way overused in many people who don't need it. The controversial question of coercive treatment also has to be understood in context.