Hi- It's no wonder his pension claim was denied-Your man presents several problems- In Oct. 1861 Nashville and Knoxville were in southern hands, suggesting your man was of Federal persuasion. Likewise, Camp Nelson, in 1864, was firmly in federal hands as a supply and staging area. The 6th Tn Inf(US) was orginized in Kentucky in 1862 of unionist from East Tennessee. Your man isn't on their rosters as listed in the TN Adjutant General's report of 1866. Neither is he listed in the 6th TN Cav, orginized in 1862 also.
I checked the CS units but they were likewise mustered at to late of date or at the other end of the state. Basically I can't find a fit for him with the info given.