There's a reason you don't use the shower for a few days. The grout needs to dry out slowly. It's like a concrete. If it's kept damp or moist, it won't fully set properly. Then, on the other hand, if you put a hairdryer to it, it will set too quickly and crack. Also, if any caulking was done, that too needs to dry properly.
I don't know how well you can 'seal' up the grout and tile but I wouldn't do it. Go visit a relative, use another shower in the house, ask a neighbor or friend, go to the gym, check into a motel, heck visit the community 'Y'. Next to a free shower, that's probably your cheapest alternative.
My best to ya and hope this helps. (3 days later ...)