If not a DVT then what? (Sorry - quite long)

[PamelaFlitton31]

I had a DVT / PE a number of years ago - there was no apparent reason for it (hadn't been on flights, no ops etc etc) and eventually I was discharged with no medication.

Since then I would say I have been back to the hospital twice a year with a pain in my calf. They do a blood test and the d-dimer result is always above normal - sometimes by a lot, sometimes only slightly.

I then have an ultrasound on my leg- no clot found. Given 5 injections of anti coagulant and a follow up scan a week later. No clot found. Told to take care and come back if it hurts again.

It is exactly the same pattern every time.

Today my calf has started aching again and is feeling tight. (No redness / swelling but I didn't have that when I actually did have the DVT.

I hate wasting the NHS's time, but I would really like to understand why this keeps happening. If it was just the pain maybe I wouldn't worry so much but it's the raised d-dimer each time that seems strange (to me), but maybe it's not.

Any ideas about what might be going on or how I could ask for more information? (once I've been told there's no clot it tends to be 'ok thanks bye' and no invitation to discuss what might be happening.