Cloudy and green

I've been using the BBB method all summer and it was working perfectly until about a week ago. Within the space of four hours the pool went from sparkling blue to cloudy green. The alkalinity has always tested at above 120, and usually at 150-180, but the pool remained clear. When I tested after the green appeared, the alkalinity was at 180. pH was a little low, so I brought it up to 7.6. Chlorine was also low, so I shocked and ran the pool for 12 hours. Turned blue but still cloudy.Next morning the green was coming back, something was eating the chlorine like it was M & M's as it was low again, and I'm right back at square one. I need help.