sudden painful lump under nipple

Over the past three days, a very painful, red lump has appeared under my left nipple.  It hurts so much I can't sleep on my stomach!!

I am a runner and wear sports bras and am wondering if bacteria could have entered.  I have been using warm compression with no luck.  Appt later in the week with doctor but am very worried.  I have a history of fibrocystic disease on that breast but this feels different.  I have three kids, youngest is 8 so haven't breastfed in a while.  
Anything that will put my mind at ease???

[zouzi]

Hi,
This sudden painful lump could very well be an infection, injury, or a cyst.You could continue applying warm compresses till you see your doctor.
As frightening as discovering a lump in or on your breast is, it's important to remember that the majority of breast lumps are not cancerous,particularly if pain is involved.
I don't think that you should be worried too much about it.The symptoms you have describe don't seem to be indicative of breast cancer.
Fibrocystic breast disease is usually a benign (non-cancerous) condition.
I hope that all goes well for you and that your doctor,after examination, will successfully treat this painful lump.
Take care and best wishes...