Big vertical crack in brick wall and loose bricks
Yes, get a STRUCTURAL engineer (not a CIVIL engineer) or an architect to look at the wall and do not cover anything up until he/she sees it. (Just pictures won’t do.) They’ll need to see in the inspection holes. 

Yes, it’s a structural issue and it’s serious and it’s going to be expensive to fix.  The good news is: it’s just the wall, it’s not the foundation. (The crack is vertical, not diagonal and there is just one.)

When this wall was built, we didn’t know as much as we know now about building materials. That wall needs some reinforcement at the crack. This wall is built by stacking various types of bricks and blocks up...but no reinforcement. Bricks are good in compression, but terrible in tension. When the wall moves, and all walls move, it creates compression and tension. Reinforcing is needed to withstand the tension in the wall.