Hey Jennifer, This is an Australian native so they do not like phosphorous in the fertiliser as it damages their roots. It sounds very much like you could have used the wrong type. (BushTucker by NeutroG is best). This could well be the reason for the leaf loss. The only thing you can try is a fertiliser with plenty of nitrogen in it (but no phosphorous). This will promote new leaf growth, but if the roots are past repair then it may just be too late. If in doubt always use Blood and Bone on natives.