Should I continue Invisalign with pulpitis?

I was on month 3 of Invisalign and my tooth, #7, became extremely painful. I've been told by 3 dentists so far that the tooth has no degradation or gum disease. Had X-ray. No cracks, cavities or anything. The Invisalign dentist said the pulp was inflamed and said to continue Invisalign new tray schedules. I was prescribed steroids to reduce inflammation. 2 months of severe pain the tooth died resulting in a gray tooth and root canal. Why was I told to continue Invisalign?