I agree with treatment to date - Neural glides/ULTT Tx of Cx and THx spine, clear all other joints 1st rib, G/H jnt, guyons tunnel- check mobility of pisiform plus night splintage.
Educate patient - no leaning on elbow, avoid heavy lifting, correct ergonomic setup.
Comfort cool elbow brace or pad maybe worn throughout day - trial with tubigip and pad of foam over cubital tunnel.
If conservative management fails - refer on to speacilist for imaging, nerve conduction studies
Surgical management - ulnar transposition