My daughter is experiencing ankle swelling, ankle pain, knee pain, knee swelling, flatfeet, calf pain and legs cramping. the following also describe her: stiff joints, difficulty walking, joint swelling, difficulty climbing stairs, difficulty getting up

See rheumatologist: Looks like she may be suffering from an autoimmune joint problem. Consult a rheumatologist.

Get her checked!: Joint pain is not normal, of course, especially in kids. I am concerned about the possibility of rheumatic fever, as one of the possible causes of joint pain. She needs to be checked out today if this is a recent problem. Or call her doc, who knows her history for advice. See https://www.mayoclinic.org/diseases-conditions/rheumatic-fever/symptoms-causes/syc-20354588

Multiple symptoms : She needs to be examined