Week 7 is day 49: on a four-week ladder that is week 3 of dose step 2, and — at the seven-day half-life this class runs on — 7 half-lives in. Steady state is about five half-lives, so day 35 is where the concentration stops climbing on its own. Day 49 is 2 weeks past it, which means the level is no longer the variable. That distinction is most of the question: at week 3 of a step, an effect that is still accumulating is indistinguishable from one that is not resolving unless you know which side of day 35 you are on. Vomiting is the rarer and more informative of the pair. It follows the same escalation weeks as nausea, so one arriving well away from a step is pointing at something other than the ladder. Dose decisions are made under supervision, and nothing here is medical advice.
Rehydration with an oral rehydration solution is more effective than water and is not the same as a sports drink.
Trial incidence for vomiting runs at roughly a third to a half of the nausea rate depending on agent and dose, and it is more concentrated in the escalation phase than nausea is.
On the detail: a practical home formulation is about six level teaspoons of sugar and half a level teaspoon of salt in one litre of water, taken in small frequent sips rather than in volumes that provoke another episode.
The caveat is that persistent vomiting is a clinical situation and this is not the place to manage one.
Small frequent sips of an oral rehydration solution, not large volumes of water.