You will probably do better with this question in the tropical fish emergency section, but...
What are your water stats?
Are the gills inflameg/differen than what they used to be?
What different foods do you normally feed you algae eater? and what is the actual name for you "algae eater"?
sounds like high nitrite level wilder helped me out with this pm him or put this tropical fish emergensis hes is a pro at things like this and will anser very quickly and correctly
what can i do