Dear friend, welcome and thanks for entrusting your query here at HCM !
You seem to have severe URTI and hence the blood in the sputum.
Purulent yellow sputum
points to infection. Do you have fever
Get a CBC done and if the leukocyte count is high, or have fever , you can start antibiotics under medical supervision.
I hope you are fully satisfied with the guidance I gave.
I would be glad to answer any further queries.
Thank you and Good luck !