Duck with black dot on webbed part of foot

[AlyDuck]

Hi everyone, I have a Muscovy duck that just recovered from a mild case of bumble foot but now I noticed that she had a blue-ish/black dot(almost resembles a blood blister) on the webbed part of her foot. It has gone down in swelling and is flat and tough feeling. She still has some redness around the area. Does anyone have any idea what it could be?

 

[AlyDuck]

This is an updated picture

 

[AlyDuck]

Hi everyone, I have a Muscovy duck that just recovered from a mild case of bumble foot but now I noticed that she had a blue-ish/black dot(almost resembles a blood blister) on the webbed part of her foot. It has gone down in swelling and is flat and tough feeling. She still has some redness around the area. Does anyone have any idea what it could be?

Also I want to add she gets worms daily, duck pellets, fresh greens and clean water daily. I have been soaking her feet in anti bacterial soapy water and apply antibiotics ointment