Technically, a sinus infection (sinusitis) is not an infection, but it refers to the inflammation or swelling of the tissues that line the sinuses. Such swelling or inflammation occurs when the sinuses get blocked and filled with fluid (mucus).
Master Investigators Box. The Master Investigators Box holds the keys (which are four rings, Katarina's Ring, Treoy's Ring, Balwen's Ring and Pithi's Ring) to the Daedric Relic. The chest is located on the wall to the North/West side of The Arcanaeum. The key to the chest is located in the Midden Dark on a table in the room with the Daedric Relic, on top of a book called Midden Incident Report. Once the rings are acquired they can then be placed on the Daedric Relic to release Velehk Sain.
The Dragon's Horn is the Dragon's Den. Look North-East of the Colliseum, and there will be an island shaped like a B with a tree on the bottom half. Take the Falcon and land on the top half. Welcome to Dragon's Den. I thought you were talking about how to get the Dragon Horn Relic. I will throw it out anyway... You can find one in Pheonix Cave. To get more, go to the the coliseum. It is at the end of the following chain: Ribbon---->Gold Hairpin<------>Dragon Horn.