Hello and thank you for the question. Answers given are for informational purposes only and are not meant to replace an exam by an in-person.
I am Dr. Sohaib, a practicing Internal Medicine Specialist and i will do my best to help you today.
Most likely the reason it fails to heal completely is because of a resistant infection that has not been eradicated. The scab forms, but the wound/ulcer deep to the scab remains infected, and keeps on secreting the fluids which result in sloughing off the scab and new one forms and this cycle continues.
Ideally there should be a swab taken from the wound site, and cultured to find the causative bug for this which will direct the use of specific antibiotics which will work best against this bug.
You can apply topical neosporin to the affected area and see how you respond to this.
Keep the affected area dry and clean.
And if this persist, does not improve or get worse see your doctor discussing the details i have mentioned to get a management plan chalked out that suits best to your needs.
You may eventually require a round of oral antibiotics as well.
I would have been worried too if I were at your place, but let me reassure you that this does not sound serious at all.
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