Same happened to me, I lost 3 days, 2 Whales for discoveries, the FoY, a Powerstone max level increase.. I was max level 59 but now I'm back to 53. I hope to god they can fix this.
Last night My Company did Whaling, killed both whales to get me to max level of 59. Today I wake up and I'm back to being an old man again after already hitting up the FoY and also max level is 53!!!