hey sharn & bk, thanks for your replies. 
ok heres the answers 2 your questions: 
didnt see any white stringy poos and i usually use rainwater for water changes  not straight tap water if i have to use tap water i use stress coat. however i havent used tap water in the last 2-3 weeks anyway. 
dont feed any beef heart, just tropical flakes, color bits & tubifex occasaionallythe other 3 discus seem fine, bright colours, eating heaps. 
cockatoo still alive but lookin sad is still in the same place as when i left 4 work. :-?