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.
Fruits and Vegetables. If you have ulcers, eat fruits that are low in acid, such as apples, peaches, pears, grapes, kiwifruit, bananas, berries and melons. Avoid all citrus, as high-acid oranges, grapefruit, tangerines, lemons and limes may increase stomach acids.