I have read other people's experience - both good and bad - using Melafix or Bettafix with bettas. From what I gather, it is thought to irritate the lining of the labrynth organ in susceptible fish. The affected betta will become extremely agitated and dart about angrily, flaring often. Again, this has not been reported to happen all the time. Some people have no problems - go figure. Maybe some individual bettas are more sensitive to the med and have a bad reaction to it?
Christmasfish, how do you use almond leaf? Is it a commercially available preparation or something that you concoct yourself?