My Mom Has A Bruise On Knee That Is Swollen

My mom has a bruise on knee that is swollen is red and blue in color and is raised. She is praline don that side so she can't distinguish where pain coming from. She cried out in pain I thought it was her foot that sometimes hurt and she kid not bump it because she doesn't get around on her own. She is with caregiver during day and with me at night.