It is not an ecchymosis . It is raised. I
Insect bite reaction, topical steroid & antibiotic,antihistaminic
Welcome to ask a doctor service
I have gone through your query and reviewed the attached photograph.
It seems to be insect bite hypersensitivity reaction.
I would recommend you to apply topical steroid and antibiotic like cortisone cream and neosporin ointment on the affected area twice daily for 7-8 days.
Take antihistaminic like tablet cetrizine 10 mg if it is associated with itching and irritation.
This will resolve the rash.
I hope to have answered your query and would be happy to answer any further queries.