I'm planning on having my first round later this year, so I'm no expert. But I know some sites give Bocox or other extras as part of a package deal, and some of those only last a few weeks. Could this be the result of something like that wearing off? It's hard to speculate when we don't actually know what you had done.
Is it an unpleasant sensation, or just not something you're used to? How has your journey been so far?