Call Southwest and ask them to add it for you. Generally, DIY adding of a TT number to your RR account after-the-fact will *not* add the TT number to existing reservations (and consequently you won't get TSA PRE on existing reservations).
While you had stomach flu symptoms, your doctor most likely prescribed a diet that consisted of bland foods and increased liquids. The BRAT diet is a common acronym used to treat an upset stomach and the stomach flu, according to FamilyDoctor.org. BRAT stands for bananas, rice, applesauce and toast.
Drinking ginger ale or ginger tea helps heal an upset stomach. Toast is another food that can be eaten during a stomach upset. However, butter, jam or peanut butter are not allowed, as an accompaniment for toast. Cutting up the toast into tiny bits and dropping them into the broth, can be a nice way of having toast. Toast can also be had along with applesauce.