I just noticed this thread because I am deep in researching Riboflavin/Vitamin B2 as being part of the reason for the breakdown of colon integrity.
There is a thread going right now
www.healingwell.com/community/default.aspx?f=38&m=2990185 which was started by someone prescribed Riboflavin for migraines and also found a UC improvement. It if is migraine that you are suffering from, Riboflavin/B2 seems to be a well researched and safe way to help them.
Dairy is one of the main sources of B2 in our Western diet and I see you are lactose free
Following my recent discoveries that I have made myself ill with over use of other B vitamin supplements, I would say try to consult with a doctor if you are going to try it.