The stinging caused by the spray is probably because your nasal tissues are raw and irritated. I bet as you heal further from your surgery, it will go away. The packets are a lot stronger than the spray IMO. My doctor told me that I can use twice as much water than the directions say for the packets, and that helps the stinging alot. But you might want to give your doctor a call, just to be on the safe side. Sorry I couldn't be more of a help.