My Mother Has Survived Stage Iv Colon Cancer And Recently

My mother has survived stage iv colon cancer and recently breast cancer with a mastectomy. She is now experiencing cold hands and feet, extreme dizziness, frequent A Fib and is extremely pale. We recently had blood word completed with her local doctor who found nothing significant. Her cardiologist did find an aneurysm in her stomach but said its not big enough to treat. Any idea what could cause the above symptoms