house cracking inside and out
The relevant professional are structural engineer or civil engineer.  Internet advice cannot suffice for a complex matter like cracking or settling, especially if there is a chance a structural wall was removed in a multistory home.  You should start by getting a copy of all relevant permits at the building department and taking photos to document the current cracks.

Your local building department may be willing to come out and inspect the home: but beware they have the ability to force you out of the home if it's unsound.