Betts fish help

[Wyckius]

I have notice that my beta fish have looks like wound or something on side .
I start treat my tank with pimaflex and melafix 6 days ago .water was good before I start treatment .tomorrow I should change 30% of water .any idea what can be to my fish ?

 

[Innesfan]

Can you provide some more info--tank size, temp, water change regimen, tank mates, what you feed, water parameters?