You may already have the two volume set "A Force To Be Reckoned With - A History of Granbury's Texas Infantry Brigade" by Danny Sessums. If not, it is an excellent source of information about the units in the brigade. Volume II has 6 appendices in the back, 3 of which list the casualties from newspapers which you already mentioned. None are shown by the good doctor. It would be my suggestion to contact Danny at www.dannysessums.com and ask about the medical records you seek. He's also has a Facebook page and a website. If anyone knows, he should.
Good Luck