What is wrong with my baby?!?

My son has been having monthly fbc's to monitor his high white blood cell count for 6 months he has several lumps on his neck and base of skull. he seems to catch every bug going. took him for tests today which i thought were going to be his usual fbc's but they informed me he needed some others doing one of which was an esr (i have no idea what this is) i know i need to be patient and let them do their job but i cant bear it any longer im worried sick and want to know what is wrong with my son. also dont know if its related but he has an inverted chest and a distended stomach neither of which they seem to have any answer for he isnt a big eater often refusing all meals and just choosing to pick at fruit although he is a good size for age i think. i am worried out of my mind please help