It Won't Let Me Continue My Quest. Help?

I'm not entirely sure if this is the correct place to post this, so I'm sorry if it isn't.

I am currently working on the frostbite quest. I made it to the part where you go into the ice cave with the blaze rod and try to find the corpse with the key. At first I misread the directions so as soon as I found a corpse (this wasn't the one with the key I was supposed to find) I figured I was done and went to go talk to Eppo.
Once I left the cave, Eppo was gone and there was no way (to my knowledge) for me to get back inside the cave. Now I am unable to complete this quest.

Also, I have a notification in the bottom right of my screen telling me to link my account when I already did so.