Chest pain from exposure to IED with chlorine gas

My son was with the Army and came in contact with an IED with chlorine gas.  He was in the gun torret with the hatch open.  He breathed the gas for approximately 20 minutes (no gas mask).  This was June of 2007.  He has been dealing with life altering pain in his chest.  He can't climb the stairs without the pain getting worse.  He is a hostage at home because he can't do anything that causes exersion.  Even speaking with long sentences causes more pain.  He has gained 90 lbs.  He is being seen at the VA hospital in Denver and they have recently started him on steriods (2 to 3 times per day) using a neubulizer.  We are suspect that this will provide him with any relief from the pain.  Is there any studies or reports that show that this will work or how long this will take?  He is only 21 years old and has his whole life in front of him.  He has been dealing with this pain for so long now he is ready to give up in having a normal life.  Do I have to worry about other diseases like Pulmonary Fibrosis, RADS or Acute Pulmonary Edema?  Answers, comments or alternate treatments would be greatly appreciated.