I'm stuck on my first clue, What was once lost should have been forgotten. Hurry and find me before I become rotten. I thought it was in the Forgotten Tomb but I searched for forever and could never find the egg. Can somone help?

You are correct.

Unfortunately, the ones that require you to fight until the game decides to give you the egg can take forever. I will occasionally go and check the easter egg hunt page just to make sure I didn't miss the notice.