I'm sorry to hear this happened to you. I would also avoid lawyers, as you're not likely to find that a cost effective solution either. The suggestion to call the hospital and negotiate is a good one. I personally would also consider reporting this doctor to the Texas Medical Board as it sounds to me like he did not follow the appropriate "standard of care" since he did no testing and seemed to give your husband a diagnosis that had what it sounds like a fairly serious emotional impact. Typically, I do not like the TMB because they are not required to talk to patients before pulling a doctor's license or restricting their practice. BUT, if they were to go through this doctor's records, it could well be that this doctor is ripping off a whole lot of other people.
That all said, if the doctor was aware that you did not have insurance he may have been trying to save you money - but he still did not do his job IMHO.
You have learned a very valuable lesson about the American medical system - these doctors make money whether they're good or bad (remember x number of doctors graduated at the bottom of the class). If only our medical system was such that doctors only got paid when they helped us get well ;)