I notice that 'ledChange' is modified only if 'url' + 1 is '?LED' this works for the first 'if' 'ledChange' search chain but will not be correct for the second further down.
EDIT:
Notice you're looping 6 times without any change to 'ledChange' so the very same 'digitalWrite' happens 6 time producing no visible change.
for ( stateCounter = 0; stateCounter <6; stateCounter++ )
{
if ( ledChange == 1 ) { digitalWrite(ledPin1, HIGH); }
else if ( ledChange == 2 ) { digitalWrite(ledPin2, HIGH); }
else if ( ledChange == 3 ) { digitalWrite(ledPin3, HIGH); }
else if ( ledChange == 4 ) { digitalWrite(ledPin1, LOW); }
else if ( ledChange == 5 ) { digitalWrite(ledPin2, LOW); }
else if ( ledChange == 6 ) { digitalWrite(ledPin3, LOW); }
}