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.
Eat two or three soda crackers before you get out of bed in the morning, the American Pregnancy Association recommends. A dry piece of toast or a handful of pretzels might also help. Other bland foods, such as a plain baked potato or a bowl of chicken broth, might also alleviate your nausea.