Get 10 yellow roses and drop roses in front of Kelcha (in the house next to Tankel) and she will tell you about her diary.
Talk with Edlera again and she ask you to find the diary.
Talk with Tankel again and he tells you he found Kelcha in Naralik.
Go to Naralik and enter the catacombs at [106, 164]. You will find 4 books close to the entrance - use them all until you find the diary which tells you Kelcha has been cursed by Mortos.
Talk to Edlera again and she tells you need 30 minor healing potions.
Go to Naralik and locate the statue above ground next to entrance of the catacombs.
Put the 30 minor healing potions into a bag in front of statue.
Use the statue and you will get a message that Kelcha is well again.