You have now gathered enough information to know that you should sail to the Vorgaard Estate. There you hope to find the diary of Eliam ir'Veldras, self-styled adventurer, and probably the last known person to have laid eyes on Jhaemast's tomb. Jhaemast himself is, possibly, the sole survivor of the dragonmarks you now bear courtesy of the strange dark mist of power, in the smoky lava-lit room beneath the temple - and his cure, whatever it may have been, your only hope of survival.