Yep....illness and/or stress can show in your readings indeed. Sometimes even before you have proper cold symptoms! If you readings go up without any changes to your diet and you cannot explain the reason for it....you might be 'brewing' up cold or something...good thing to know..
Keep eating low carb way and the blood sugars should eventually respond and go down again when your body is up to it. Even if you were taking glyclizide...you would quite likely have to face the same issue...blood sugars go up when we are poorly.