Even if you DONT have any flu symptoms!!
I was waiting to feel unwell before I went to doctors (at Health Visitor's advice).
I was using heat before / during feeding.
I was massaging towards nipple.
Etc (@ HV's advice).
Went to doc cause I felt it was not getting better last week. Rushed to hospital for IV antibiotics, drain inserted to boob. I have an abscess with sepsis and mastitis, infection spreading round other side of boob too now.
Don't be like me and wait - see your GP.