Since you have access to an attorney, I would ask them how to respond to ""Very concerned that they were not made aware of any medical conditions I had during the hiring process..."

It sounds illegal to me as well but I am not a lawyer. Fortunately you are in a field that is in good demand and once you are well again you can look for another job. I would be cautious about working those kind of hours again. When my son was interviewing we looked up most places to get reviews from workers and could get a heads up about what to look out for.