I have been looking for information on my grandfather for over a year now and thus far I've been able to find nothing, so I thought someone here might be able to offer up something...

My grandfather, Bernard Steven Kramer, was born in 1917 in Illinois. I don't know when he enlisted but I know that he served in the Korean War and was a POW and on the Bataan Death March. He actually escaped while on the march and was taken care of by a 'tribe' for 7 years before returning home to learn that his wife had died in the war and that his son was just gone. Weird story, I know...
My grandfather never talked about this but my father does have the hat he wore in the jungle while a POW and his Purple Heart. He also remembers that his father had scars up his back from bamboo stalks being driven up his spine. My grandfather passed away in 1975 from a complication of diabetes, something he developed while living in the jungle.
We do have a picture of my grandfathers unit and it reads this:
E Btry
3rd Field Artillery
Ft. Sheridan, IL
April 1938

I've sent off the proper forms to the NARA but they were able to find nothing for me. I also know that he was a drill sargeant and my dad grew up all over the world. My grandfather retired during the Vietnam War...
I know my information is spacey and all over the place but any help would be greatly appreciated...