Re: Blood/thick pus squeezed from nipple. OUCH!
I have a friend who had the same thing and she was diagnosed with intraductal papilloma. non-cancerous, but she's screened often.
But what you describe could also be a symptom of a breast cancer. One doesn't know until tests are done.
Since you've had lots of mastitis, it's possible that this is a more intensive infection...
What colour was the pus? white? green? yellow? brown? black?
Let us know the outcome please.
It's all a matter of perspective!