Hi M.,
Sounds like you're doing everything you can for your little girl. You didn't say how long it had been between stopping pumping and the painful lump coming along. If you stopped cold turkey and it's only been a week or less, it sounds like you are probably dealing with a clogged milk duct, which you need to deal with or it could become infected and then you have mastitis, not just a plugged duct. You should use moist heat, as recommended below, and pump or hand express to try to clear the duct. Every two hours or so. Your daughter would be the best to clear the plug, if you and she wanted to do try it, if you could position her so that her chin was toward the lump. If not, I know that I successfully cleared many a plugs with hand expression, so that will work, too. I found filling a big bowl with hot water, sitting it just below chest level, and immersing my breast in it the most effective moist heat solution. You will have to find what works for you, as there is usually one thing that works best for each person. The washcloth and shower were never focused enough to deal with my plugs.
If this is a plugged duct, you can contact a local La Leche League leader www.llli.org, to not only get other tips for clearing the plug, but also tips on how to wean yourself off of pumping so that another plugged duct doesn't occur.
It can take months to completely dry up. It happens gradually. Good luck and enjoy your little girl!
H.