I am a female veteran of OIF. I was in Iraq 2 years ago and when I returned it was difficult and still find it difficult to connect with my family and others that do not understand what I experienced. At times I feel very detached from reality, and I have not been diagnosed with PTSD either. I don't know if this might be similar to what you are dealing with in regard to your husband, but it could be similar. Living and working in a combat zone can drastically affect a persons view of life, and I am speaking from experience.
Men are very different than women when it comes to dealing with their emotions. So your husband may not feel comfortable talking to you or anyone else about what he experience or currently feels because it is so drastically different from reality. If your husband is like most military members he will not even discuss his feelings with others in the military because it could make him look weak. Also, he may not even be aware of what he truly is feeling because he is a man and does not want to explore his true feelings and admit that things have scared or affected him the way they did.
One suggestion that I would offer although you may have already tried would be contacting a local vet center which specializes in treating and working with combat veterans. It is separate from the VA and confidential even though it falls under the VA. I know that every vet center offers different services depending on staffing and location, but it might be helpful to you and your husband. I have started using my local vet center and have found it to be very helpful to me in dealing with all of my emotions. Here is a web link that can provide more information about vet centers http://www.vetcenter.va.gov/
I hope this helps and if you have already tried this resource there may be others that offer special services for OIF vets in your local community and state. So I would start by researching support groups in your area for OIF vets.