All Blind walls need to use a waterproofed paint. Go to finch Engineering, They will help. If your structure is stable nothing to worry. Wall cracks can come due to material ( Sand) issues. That can be coxed with nets and paint.
I am not a civil Engineer, But consult a Civil Engineer. If you don't know contact IESL, they will give list of names in your area. Don't work on advice of Makabass now which will cost more.
Talk to a chartered Civil Engineer. Seems this building doest have a structural design.
Dont Depend on Bas. Pay 20-30,000/- to a structural engineer on foundation, columns, beams and slabs. Its worth than trying to fix these type of issues.