Also, make sure the dirt is graded properly from the edge of the house in that area. Check all downspouts as well and make sure there isn't an abnormal amount of water draining at that area before you start getting into the heavy work.

I would be concerned because it will only get worse. I would try patching the wall from the inside with hydraulic cement. If that doesn't work, you'll have to dig down outside the house to fix the crack from the outside and apply waterproofing to the concrete block.