Since you are an end unit, and the only unit with reoccuring cracks in your walls, your unit was probably built upon the end of a slope.  It is likely that more fill was placed under your unit prior to construction to bring it up to the needed grade.  To stop the settlement, either a helical pier or hydraulic pier would be the best solution.  They typically drive 14ft to 28ft in our area.  It used to be general practice to underpin the foundation with 3ft of additional concrete, however this sometimes does not fix the problem.  The fill beneath the townhouse could be 10ft and it would still settle.

Most of us never give our unfinished basements a second thought unless there is water trouble.
Wouldn’t it be nice not to worry about basement flooding or basement leaks that damage your
furnace, water heater, washer, dryer and personal belongings.
Keystone Basement Technologies can solve your basement water problems.
Our basement waterproofing system carries a
LIFE TIME WARRANTY that is fully transferable from home owner to home owner with no transfer fees and no additional cost to our customers.

“Your employees did a great job. With all this rain, we have already accumulated water in the sump pit. Without it we would have been flooded again. Thank you again.”
Ed Loeber