Mildew: "Horrible dragons! How could they do such a thing to my poor sheep? My poor Fungus can't move--he's as stiff as a board!
I found him lying on the ground over there. Figure out what happened so you can fix what your dragons have done."
1- Find out what happened to Fungus
Mildew: "A dragon claw! See? I told you it was those blasted dragons."
2- Talk to Hiccup
3- Talk to the Botanist at the Lookout
4- Find the skullcap and lobelia plants in the Wilderness
Phlegma: "Those are correct. Well done!
Now we need to mix these plants together to make the medicine. Take them to the lab and talk to Heather."
5- Talk to Heather by the Lab
Heather: "Giving medicine to a paralyzed sheep is not easy. We need to find some way to get the sheep to eat the medicine. Let me think about this for a minute..."