T.R.
First of all, take a breath. You are doing the right things, first by taking him in to a clinic when he wasn't feeling well, & then by following up with your regular doctor for consistency of care.
The elevated ALT is a liver test, to detect liver injury. This can occur when people have exercised too strenuously, or if they are on drugs at a dosage that their body is unable to metabolize properly. It can even be due to growth spurts in young children. A repeat of the blood test to see if the levels are consistent, or if it was just a peak that got caught would be appropriate.
http://www.webmd.com/digestive-disorders/alanine-aminotra...
The low neutrophils is concerning however. These white blood cells are what fight off infections in the body. If they are critically low, it means that either he isn't making them properly, or he has been fighting a strong or chronic infection to the point where they are depleted. Hopefully the blood work next week will show an improvement.
In the meantime, take a look @ this website for information on how to protect him from infection risk, since his immune system isn't where it should be right now.
http://www.upmc.com/patients-visitors/education/cancer/pa...
Praying that none of these indicators result in anything serious, & your little man is doing well with a bit of time! T.