i have similar symptoms....bad migraine headaches...and a positive d-dimer. What ever happened? Did you get a dx?
Usually an eleveated D-Dimer means you have a clot somewhere, it does not say where, but it is a signal to the doctor that you could have one.
I found this doing a google search:
What does the test result mean?
"A positive D-dimer indicates the presence of an abnormally high level of fibrin degradation products in your body. It tells your doctor that there has been significant clot (thrombus) formation and breakdown in the body, but it does not tell the location or cause. An elevated D-dimer may be due to a VTE or DIC but it may also be due to a recent surgery, trauma, or infection. Elevated levels are also seen with liver disease, pregnancy, eclampsia, heart disease, and some cancers."
In answer to your question regarding the recent surgery, yes, it could be due to that.
Hope this helps.