"Lameness" in my beef cow

[x807]

This past weekend I noticed my 5 yr old beef cow was limping/favoring her back legs. It's been a mild muddy winter here in the north not like usual. I took her out and cleaned her up with a wash removing the mud tags on her legs down to her good. The bottom of her leg was packed with mud. Once she was all cleaned up I noticed down on her hold where her hoof splits there was a white swollen bump there that I never seen before. Could this cause lameness, how do you treat it ? Please see pictures for better description

 

[M-5]

No pic

 

[Alan]

Certainly need a pic, could be one of many problems, otherwise it's a blind guess.