Unholy took a hit with the patch, but that was to bring it in line with frost, not worse.
All I can say (since armory is down, if you post up a wowhead spec that would help) is that you need to be managing your CDs well as a DK tank, especially if your in entry lvl gear. I mean, in full T7.5 I still use BS precasts and IBF at the start of hard hitting big pulls. Doing that smooths out the dam because as the mobs die you IBF will fall off and then its just one or 2 mobs hitting you. Plus I chain pull so I do it to save healer mana :P
I cast the spells that make the people fall over.