Family housing near San Diego Children's Hospital: 3 weeks

My son Nathan has been accepted for treatment at San Diego Children's Hospital in San Diego, starting on Tuesday in November. We live 198 km away in a village four hours away, and hotel costs would use up what we have set aside for the treatment itself. We're looking for a room, granny flat or short-term rental within about 30 minutes of the hospital, for 3 weeks. Two of us would stay: Nathan and me. We can contribute $135 a week and cook for the household if you'd like. Nathan will have some immune precautions, so a clean, smoke-free place would be ideal. A kitchen is a bonus. Thank you. Thank you so much.