I'd guess caffeine and sugar are "considered no-nos" because caffeine acts as a stimulant on the intestines and can make diarrhea worse for some people and a high sugar intake is a known risk factor for IBD. It can also make an intestinal ecological imbalance (usually candida yeast) much worse. Individual tolerance will vary, of course.
In addition to a B12 injection, you might also research herbal energy boosters like ginseng. http://www.lifescript
.com/Health/Alternative-Therapies/Herbs/Ginseng_Herbal_Energy_Booster.aspx
And make sure your iron levels aren't low.
Running or getting some other exercise in the a.m. is a good suggestion. You might also consider a morning yoga program designed to stretch and energize you. You'd be surprised how good it feels.