Mouth ulcers, acne and itching in anus.

I have a healthy lifestyle. I exercise about 4 days a week, have healthy breakfast (dalia/oats etc), have a light lunch (3 rotis, 1 sabzi, 1 dal, no rice), have a homely dinner (3 rotis, 1 sabzi). I have very little sugar and consume warm water, green tea, methi seeds and aloe vera juice daily. Still, if my food cycle gets interrupted for 3-4 days, let's say I have to eat outside continuously or am travelling and all healthy habits have gone for a toss, immediately I get mouth ulcers, itching in the anus, facial acne, farting and abnormal stool (form, shape and colour). It takes a few days of getting back to my old lifestyle for all these symptoms to go. This has been happening for a couple of years now and happens every single time. What do I need to do?!