Another Plea For Help With Germany

This stamp was canceled at Schwerin in 1900 and at bottom there is a fragment of a parenthesized locator that looks to me like "...MERN."
Schwerin is now in the state of Mecklenburg-Vorpommern, but that didn't exist in 1900. The "...MERN" fragmentleads me to believe that the whole locator was "POMMERN." But Schwerin wasn't part of Pommern (Pomerania), was it?
Also, Geonames tells me that there have been a couple of places named Schwerin in Brandenburg. Could it have been one of these?
My thanks in advance for any hilfe anyone can give me.

Schwerin,Pommern.
Most likely Zwierzynek,now in Poland.

Ahhhhh, thank you Vayolene!
My searches had turned up another former Schwerin (an der Warthe) in Poland, now named Skwierzyna, but it had not been in Pomerania. None of my searches had turned up Zwierzynek.
Put yourself in for a raise!