I was farming in The King's Passage using the Jester's Hat and the Covetous Gold Serpent Ring +1, but at the same time I had the Jester's Gloves and the Covetous Silver Serpent's Ring +2 on as well to boost my soul collection. I was also consuming Rusted Coins with every run to help boost the item find rate.
After all 7 runs (the enemies had stopped spawning) all I had found was one Stone Parma and a set of Llewelyn Leggings. That's pretty terrible considering the last few times I ran through there I managed to get at least 4 shields, 2 armour sets, 2 stone twin blades and 3 titanite slabs.
Is it possible that my soul farming gear was interfering with my item farming gear?