Thanks for the query.
Kindly meet a Dermatologist near you for diagnosis and treatment plans. Similar presentation can be seen in many skin diseases and can be diagnosed during a consultation. OTC anti-allergic medications may be useful till then. This looks a skin infection and not a blood clot to me based on the photograph. Meet a Dermatologist to decide on need of an antibiotic.
Your dermatologist will decide a treatment plan for you after a consultation.