The discharge is very minimal. Could this still be the cause?
Yes, especailly when a blocked duct is going to minimize the secretion.
The discharge is definitely sticky, but there is no warmth.
The discharge should be thicker than normal if ectasia or mastitis are present. And a minor infection may not generate enough warmth to be detected, especially if deeper. So this is not really definitive.
My doctor said the discharge might be from a blocked duct. She also said she thought the pain and discharge weren't related.
First of all a blocked duct and possible infection from the blockakage is going to cause pain.
Secondly if the doctor cannot tell you what is causing the pain then how would she know that the pain is unrelated?