What Causes Severe Swelling In The Feet And Ankles?

57 year old female, non small cell lung cancer surgery August 1st. Mass was about 4 cm. Had 2 chemo treatments and kidney function was effected. So her chemo was put on hold. She needed 2 units of blood, iron shots, potassium, and hydrations all through her port. She needs oxygen and is waiting on approval from Medicare. Her sitting oxygen level was 98 and then dropped to 69 when she went for a short walk. Both her feet and ankles are extremely swollen up to almost her knees. Her left breast is swollen 7-8 times it s size. She has no pain unless touched. Feet and ankle swelling--no pain she says. She has high blood pressure and takes meds for that.