My Son Has Had Several Problems In The Past Two

My son has had several problems in the past two months, beginning with pneumonia, then an abscess in his lung, then a blood clots in his leg and lungs. He has now been diagnosed with a bowel build up, mot a blockage. He is eating very little and very, very lethargic. He is in eloquis, and a stool softener and Miralox. How long does it take for this build up to pass?