mate if you had a solid block of ice over your drain pan in freezer this is your problem, its a cheap design fridge and commonly happens here that the drains ice up after a period of time then every defrost the ice builds and eventually blocks your return air vents for the fridge section thus allowing air in but no air out and not completing your air circuit, i would do exactly wat you suggested ... make a habit if checking drain tray (outside of fridge) for moisture when this drys up do your shut down for 2 days, if i had a dollar for every time ive seen this fault i wouldnt be still fixin fridges lol, some companys have a field fix which involves drain heaters etc but are often in my experience un succesfull, moniter your fridge and if you loose cooling in 2-3 weeks again if ice is on your coil you have a defrost prob, if ice in drain again call company and see if field fix avail and approx cost good luck sounds like its not a major fault anyways