Shelly, If he died at Camp Nelson in Arkansas he would probably have been buried there in the Confederate Cemetery. Camp Nelson is located in Lonoke County in the Austin area. Measles and other diseases hit the Camp. I know the Camp contained units from Texas, (10th Infantry, 13th Calvary), but I do not know all the units that were there. I did not find his name listed. But the cemetery contains unknown soldiers.
Confusing matters is there are other Camp Nelsons. If he served in Kentucky and died, it is possible he would be buried at that Camp Nelson. I am not familiar with the location of a Sidney Johnson Camp in Arkansas, but I do know of a Camp Sidney Johnson that was located in Chambers County in Eastern Texas.