Do you know what temperature she used? It should match body temp. Slightly cooler water is used later in the session to trigger perstalsis. If the water was cool throughout the session it's no wonder you cramped. If you don't feel comfortable with your hydrotherapist, get another one. They are not all equal in aptitude.
Does her unit have a temperature gauge? Some units don't which is far from ideal. Also make sure the unit had great filtration including ultraviolet light.