This has happened in my GE side-by-side (model GSS20IEMDWW). For me, the problem was caused by a faulty temp sensor in the fresh food side. That sensor never signalled the computer that the temp in the fresh food side was cool enough, so the compressor ran constantly.
Since the compressor was running constantly, the evaporator coils (back wall of the freezer compartment) eventually iced over (took about a week). Since the fan that draws air over the evaporator coils could no longer move any air (due to the icing), the temperature in the fresh food side continued to climb. (The fresh food side is chilled through a hole with a motorized door at the top of the dividing wall, so if no air is moving in the freezer compartment, temps in the fresh food compartment climb.)
I replaced the temp sensor in the fresh food side and solved the problem for a while. About six months later I had the same problem again, so I replaced both temp sensors in the freezer compartment - which solved the problem again. (My fridge is about seven years old.)
If you are going to replace any of the temp sensors, replace them all under the principle of "if one failed, the rest will soon fail too".
This site has schematics of various appliances, including the model number you provided...http://www.partselect.com/AdvancedModelSearch.aspx?ModelNum=GSS22WGPDBB&mfgModelNum=&fkMfgID=2
Your model appears very similar to mine - in the "Fresh Food Shelves" section of the above site, the sensor is diagram number 242. In the "Freezer Section", the sensors are diagram number 241 and 243.