What could it be?

[patsy999]

I gave up smoking in january as i was in hospital for oxygen levels of 86% and i have COPD.
In April they found a heart murmer, so waiting on heart scan results.
Yesterday i went to GP with swollen feet and legs and shes ordered a doppler scan and a blood test, but didnt tell me why.
Im 56.

Possibly a NT-proBNP blood test. Just to check that the swelling isn’t due to heart issues. The doppler will tell them if it’s safe for you to wear compression stockings to help with the swelling or if a vascular team need to do further tests.

Did you ask why? I'm sure the doctor would have explained if you asked.