About a month ago my cat had a lump on her head. It was about the size of a pea when I noticed it. Over the past couple of weeks it tripled in size. last night it came to a head and a ton of pus came out of it. whenever I wiped it off her head more would come out. today the lump is about the size of a pea again, but pus and blood are comming out of it. It doesn't seem to hurt her or bother her at all. Is this something that I should be concerned about?