It is a fairly common theme in fantasy literature that elves, sprites, and the like once inhabited this reality, but went to another reality as the weight of humanity began to press on them. The Wandering Jew is an old legend. Geoffrey Chaucer was indeed an important diplomat at King Richard's court. A spittard is a young deer. This is Hob again.
Rheum is a cold or runny nose.
Catarrh is much the same. It seems quite modern for Hob to be saying it in 1489. Henry VII was the first Tudor king of England, presumably named Richmond before he assumed the throne. Will Shakespeare, himself. An iamb is a foot with one short or unstressed syllable followed by one long or stressed syllable.