Trace Adkins has left rehab -- just 2 weeks after he entered the Florida facility for alcoholism ... TMZ has reported this afternoon

Sources connected to Trace say his father is seriously ill and he felt he needed to be at his bedside ... immediately.


We're told when the illness resolves itself ... Trace will then decide if he goes back to an inpatient program or does outpatient therapy.

  For the meantime,  Trace asked his therapists in Florida to put him in contact with counselors near his dad.  Prayers please for Trace Adkins.