Blisters on the inside of her leg?

I am Geaton and willie here. Does Mom suffer from diabetes too? With diabetics sores take a long time to heal or they don't at all.

Agree with cwillie to please contact your healthcare provider and set up an appointment with a wound care specialist.

If by "disinfectant" you mean something like hydrogen peroxide, you need to stop using that. It actually prevents wounds from healing.

" If the wound is minor enough to be treated at home, antiseptics such as hydrogen peroxide, rubbing alcohol, Purell, iodine, salt, or baking powder should never be applied to the wound. While antiseptics effectively kill bacteria with little harm when applied to the outside of healthy skin, they do more harm than good when applied to wounds."

Source:
https://wtamu.edu/~cbaird/sq/2013/04/04/how-often-should-hydrogen-peroxide-be-used-to-treat-wounds/#:~:text=Hydrogen%20peroxide%20should%20never%20be,does%20more%20harm%20than%20good.

This is not a DIY project, she needs to be seen by her doctor and professional wound care. I'll link an article that explains about these types of ulcers

https://my.clevelandclinic.org/health/diseases/17169-leg-and-foot-ulcers