Sorry to hear you're not feeling well and frustrated, we can relate.
To this point the only (I use "only" lightly, it's enough in itself) testing completed on you to check for activity and or inflammation of Crohn's has been blood work and a Colonoscopy?
They need to go beyond those tests and if you're not happy with what's been done and the results, I definitely recommend requesting the rest of the tests to be completed. If your current GI doesn't want to comply, see a different GI for a second opinion.
We recently have discussed the tests that need to be completed to indicate an issue with Crohn's, which are also used to rule out Crohn's.
Here is the thread if you would like to have a read-www.healingwell.com/community/default.aspx?f=17&m=2511307
Let us know how things go and best of luck!