Morning happy new year, you really need to ask these questions to your Gp, I am not a Doctor but I would have thought a DVT behind the knee is just where your blood clot was,being on a warfarin isn't to bad at least it will save you from having another clot.
I test my own blood I bought my machine and luckily the Gp prescribes the test sticks
I have Hughes syndrome so my INR has to be in the range of around 3.5
It might be worth a look at the site on here or the Hughes foundation site.
Content on HealthUnlocked does not replace the relationship between you and doctors or other healthcare professionals nor the advice you receive from them.
Never delay seeking advice or dialling emergency services because of something that you have read on HealthUnlocked.