Parts of the Lehigh Valley sit on limestone bedrock, which slowly dissolves as rainwater soaks through it. That is why sinkholes appear in the region from time to time, and it is one reason a new crack or a sudden change in how water enters a basement deserves a proper look rather than a tube of sealant.
A thin vertical crack in a poured wall that only seeps after rain can usually be sealed by injection from the inside. Cracks that run horizontally, stair-step through block, are wider at one end, or keep growing are different: they can mean soil movement or settling, and the right first step may be a structural engineer. In your request, say where the crack is, how wide it is and whether it has changed recently. A reputable contractor will tell you plainly if the job needs an engineer before any repair.