Very sorry to hear your symptoms. I have seen quite a few patients who develop allergy
. It is difficult to advise the treatment without taking a look. You might benefit from seeing a dermatologist
as soon as possible. A lot of times such lesions get better by applying topical steroid
and antibiotic (both). However, since the lesion occurred with a blade, there could be an infection as well. In addition, you may need a tetanus
shot depending on the level of wound, if you haven't received one in last 5 years.
Hope that helps. Take care and be well.