My home is approx 30 yrs old and has a ceramic tile shower. Recently, about 12 inches from the bottom of he shower wall the tiles began to bow out. Cracks in the shower grout noticable. Attempted to recaulk. Worked for a little while. Now the tiles are coming out. What is the most econical way of repairing? Would it be best to remove all the tiles and install a fiberglass shower enclosure or attempt to continue to regrout tiles as they become loose?