I'd also suggest you Google VA diagnostic code for "X" (whatever your seeking a disability for) ex. sinusitis, knee, back). Notice what are the symptoms that the VA calls out and how they result in a rating. For example a diagnosis which calls out you take medications may have a minimum rating of 10%, while the next highest rating calls out additional criteria. Remember you need a current diagnosis, an event or illness in the service such as str's, etc,. and or buddy letters, and thirdly, a connection or nexus that connects the first two. The third leg you need a doctor or medical opinion that makes the connection. But Shrek is right, the longer you go, the more $ you leave on the table with the VA.