While a doctor's opinion is number one in this situation and must be used, I'd also like to suggest that it is possible that your wife has vaginusmus. Vaginismus causes painful sex. It can cause a strong burning sensation that only starts when penetration is attempted and stops when penetration stops. It can also feel like your penis is hitting a wall. Vaginismus is very hard to diagnose because it is a subconscious tightening of the PC muscle due to the brain "protecting" the vagina from harm. If a female is able to successfully complete a gynecology exam, the doctor could tell her she is perfectly fine and not diagnose her with vaginismus. She could even be unable to complete the exam because of pain but the doctor sitll might not be familiar with the condition or diagnose her. Vaginsmus is not something your wife does on purpose. It can be caused because of strict religious upbringing, past painful experiences with attempted penetration, fear, anxiety, a number of issues. I strongly recommend visiting vaginismus.com for a kit that will help your wife work through her problems. They sell a video, book set and dilator set that your wife can use to help her cure her vaginismus. Of course, if the problem is not vaginismus, only a doctor can tell her that. However, if she has gotten a clean bill of health then I would consider this your next step. I totally sympathize with what you are going through. I also have vaginismus and it is a very alone feeling. I went to many doctors and therapists asking about my problem and no one said anything was wrong with me but yet, I felt there must be something wrong. I finally found out about vaginisums from a forum similar to this one and the symptoms matched perfectly with my experiences. Unfortunately, I think many doctors don't consider it because it is not a physical disease and it is so shameful for so many women that no one who has it discusses it.
Also, I just read through all the responses and I am so sorry that you came on here looking for help with such a difficult and embarrassing problem and ended up getting flamed for your religious beliefs. I don't think you meant to start anything. People can just be jerks because they don't have to see you through the internet and it's fun for them to get offended I guess. I really do hope that you can are still having these responses emailed to you because I want you and your wife to get the help you need and I want you to be able to check out the vaginismus kit. I'd love to hear an update if you are still reading these responses.