As mentioned, nausea and vomiting are common symptoms of anxiety and stress. While vomiting can be a symptom of anxiety, it's not as common as nausea. Behaving anxiously activates the stress response.
On December 8, 2016, Cinemax and Sky1 announced they had greenlit a brand new series of Strike Back with a brand new cast, no longer focusing on former stars Sullivan Stapleton and Philip Winchester. Daniel MacPherson, Alin Sumarwata, Roxanne McKee and Warren Brown have been cast to star in the new series.
But that changed this season; for the first time, the series made an honest effort to develop the men at its heart, and it worked. That's not to say Strike Back hasn't attempted to raise the personal stakes over the years, but it always felt like the action and mission came first and the character evolution came second.