I am having blocked nose for three-four weeks, I consulted a nearby doctor. He gave me nesocad nasal drop, lecope and a vitamin c chewable tablets, the problem is whenever I use this nasal drop I get relief for 1-2 hours and after that my nose becomes dry and sneezing starts and then again my nose gets blocked. The same thing is happening from a couple of weeks. So what should I do? Is this a symptom of sinus or any other big disease?