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Better should be moved to a hospital with speciality care mainly cardiology, because patient with previous history of DVT should maintain the INR at least "3".
Depending upon the INR value the dose adjustment of oral anti-coagulants will be adjusted. As per given data your INR target has not reached thats why there is a recurrence now.
Now, i suggest you to take him to a Cardiologist and get done the Doppler ultrasound
the treatment ASAP.