[Ger-Poland-Volhynia] Endings "SZICK"

[Georg Friederici]

I'm trying to find the rigth explanation for the familynames with endings as: 
.                                                                    . 
SZIK ............ f.e. in Friedriszik, Frederiszik  
SZICK .......... f.e. in Friederiszick, Frederiszick 
SZIG ............ f.e. in Friederiszig, Frederiszig 
.                                                                    . 
Somebody can help ? 
Greetings from Santiago de Chile 
.                                                                   . 
Georg Friederici 
www.friederici.de.vu 
.