sick betta :(

[guppygirly]

One of my females is sick. I just had a betta die a week ago after a long battle with swim bladder and fungal infection. I really don't want a repeat of that incident. So here are her symptoms, well symptom actually. There is a small tan dot on her side, up close it looks like the scales are spread around it, but just in that tiny spot. Any ideas?

edit: So far I have done a 50% water change and added salt. She is in a 2.5 gallon minibow. All water parameters check out ok.