I have to agree with quincy - from my own personal experience, let her eat what ever she wants, when ever she wants. She will work out for herself soon enough which foods make her symptoms worse and she will learn to avoid them.
Keep a food diary (as best you can) as it can help work out intolerences. The faster way as Judilyn suggested is to just get the GI to test.
Also with regard to pasta - its a great source of carbs and even the bigger companies are now producing gluten free versions of their pasta which you can find in the health food section of the bigger super markets.
In said health food section you can also find gluten/wheat/sugar free chocholate, cerials, chips, biscuts, snacks etc. Just read the ingredient lists on the back of everything.
Learn about fibre
as its important to keep up the Soluble fibres and reduce the Insoluble. Soluble makes things more comfortable, insoluble makes things less comfortable - especially when in a colitis flare.
Final suggestion is not to cut everything out eg. bread etc. Just try to keep it to a minimum unless you know there is an intolerance to it. My take is that what you eat doesn't affect the colitis itself at all. It only increases or decreases the colitis related symptoms such as gas and D.