Shelly
If your ancestor died in Nov. 1862 the 18th Texas was at Camp Nelson, at Austin Arkansas. Whie many men died and were buried at Camp Nelson, many of the sick were also sent to Hospitals at Little Rock.
A third slight possibility is that in late November 1862 plans were in the works for these Texans to move to Pine Bluff in support of Arkansas Post. Some of the 18th Texas died at Pine Bluff Hospitals by Christmas.