Try taking a **paracetamol**. Although it is mainly a painkiller, it also has an anti-inflammatory action too. This can help by reducing swelling and that can affect the nasal membranes. 

What we consider to be a "blocked nose" is usually nothing of the sort, it is soft tissue of the nose swollen up and blocking the airway all on its own.

I used to suffer from hayfever and once or twice tried paracetamol to help with sleep and it seemed to work for me.