Not Sure How to Help My Betta

[Neez]

Hi everyone, Im currently worried about an injury/disease my betta has and Im really unsure on what to do. My betta lives in a 5 gallon, heated, cycled tank and Ive had him for a few months at this point. A few days ago I noticed a white mark on the base of one of his fins. I thought it might heal itself but it hasn't and I cant figure out what it is. It could be white spot but theres only one and when I look up close as it it seems swollen and theres a purplish colour around it. If anyone has any idea what it could be please let me know. My betta has been a bit quiet today but is still able to swim, eat and is attentive.

Ive attached photos below as well as the medical products I have for him. My town is currently surrounded by bushfires so getting other products is tricky but if none of these medicines will help I can at least try to get something more useful. Thank you

 

[Neez]

My betta has begun not using his fin that has the injury on it. Hes keeping it clamped against his body not. Please does anyone know what to do?

 

[lilmich]

I'm going to start off by saying I've not seen this before, so if anyone more experienced comments, feel free to go with what they advise.

I think it's been mentioned the -fix products damage their labarynth organs. Is that bathing salt the same thing as aquarium salt?

My usual place to start with illnesses I haven't encountered before is aquarium salt 1g per liter (or people on here say 1 tablespoon per gallon), indian almond leaves and methalyne blue. I usually do a 50% water change right before adding all of this.

Are your water parameters ok?