You can obtain your paperwork and discharge through the VA. If you have received care at a VA facility or Hospital they usually will ask for a copy of your discharge paperwork at the intake admissions of the VA.
You can also use the website https://www.ebenefits.va.gov/ebenefits/homepage
Use to column that says "Manage Benefits" select the category for "VA Letter" if you already have been awarded the 25% disability rating you can generate the document using that tab. If you are not currently enrolled in ebenefits I suggest doing so. As a veteran myself it is very easy and you can also order your medications and message your VA doctors.