If tiles are popping loose that is a installer error. Schluter Kerdi has a minimum size for tile allowed on their foam trays if that is what was used. In progress photo's would help. Keep in mind you just had someone learn on your project so a less than perfect outcome is not surprising.

Wall tile, floor tile or both? I believe I see the top of a tub?

First photo is the floor? That discoloration in the grout would suggest a shower pan problem (not draining properly). The tiles popping loose, yet another indication of improper install/prep. Sadly, that is a re-do. That wasn't a qualified tile contractor, and the General Contractor, if he hired him, should be liable for the tear out and re-build. Redoing grout won't fix that. Is that grout in the niche at the change of plane? Should be silicone caulk. Lots of red flags here. Sorry!

way to go dragon Speaking up

Your tile work is on par with the term "Builder" cheap cut of tile, cheap materials and the cheapest hack install they can find.