When you were feeding it every other day..did it eat the food you were offering? You really should feed it once every three days, like no more than three times a week. Any more than that you could be overfeeding your anemone and cause water quality to go down. Did your bta loose its zooxanthellae? Could you post a picture of your bta? When you said your anemone looked like it was dying for a couple of days. It was just trying to get use to its new home. They deflate to change the water in their bodys to acclimate themselfs to the tank. When you see it spitting out brown strings of stuff...thats poop. The more you feed the anemone the more it does this. Is your bta still sticky as in does the food still stick to it?
What brand of silversides are you feeding your bta? I have noticed with my lta that I have now and btas I have had in the past..didn't like ocean nutrition silversides. They really liked sanfransico bay brand silversides though. Also, my anemones would quit eating silversides once they have been in the freezer a little over a month. If you have just bought the silversides and the anemone still won't eat it. Start spot feeding mysis shrimp every other day.
To get to know a lot about BTAs go to this web site
www.karensroseanemones.com