Oil leak

Car was making whining sound, mechanic replaced PCV valve Thereafter noticed oil leak. Mechanic replaced crankshaft gasket. Oil still leaking. Also intermittently blowing smoke from exhaust.

I must also add that the car had no problems or oil leaks prior to the mechanic replacing the PCV Valve (Positive Crankcase Ventilation Valve). After investigating the oil leak the mechanic replaced the crank shaft gasket or seal. Not solved. Oil is still leaking from somewhere. Also intermittently smoke blowing from exhaust.