I'm pretty sure it all depends on the severity of her crohn's. I know that you can go online and apply for disability. They will more than likely give you a hard time b/c of her age. Most likely she will be denied the first time and you will have to appeal it. Once she has been denied you can contact a disability attorney and they will handle the case for you (submitting medical records, etc). And the attorney's usually only get paid if she gets approved for disability. The disability office would take the attorney's pay out right off the top and then deposit or send your payment. I do know that now days you don't recieve the full amount of back pay, they send it to you every few months. And back pay is done by the first day you file.
Hope this helps.