Im 33 and diagnose has a cyst on left kidney.i also felt numbness on the left midback?

Not uncommon: Kidney cyst are not uncommon and they can present with back pain. Can be caused by stones blocking egress. It should be measured and followed by a urologist.

Cysts: Cysts can be completely normal and benign. A cyst (actually anything kidney related) should not cause numbness in the back. If there is more than one cyst (at age, 3 or more cysts), it can be a sign of polycystic kidney disease, but a single cyst is usually not a problem.