Hi Melanie. Your daughter is right. A lot of these issues that your son has developed could be related to PKU. Issues with untreated PKU or high phenylalanine levels can range from a lack of energy, poor concentration and attention, issues with memory, mood swings, irritability, depression, tremors or shakes, eczema (skin rash), seizures in infancy, and so on. It seems like your son could be experiencing a few of these issues at the moment.
It is very possible that your sons levels are higher today than they were years ago. When he was younger his appetite was probably smaller than it is today, meaning he could have been eating less protein when he was younger. Protein is what makes phenylalanine levels go up in people who have PKU.
My suggestion would be to have your sons phenylalanine levels tested to see what they are at. The recommended range for people who have PKU is 2-6 mg/dl. If phenylalanine levels are any higher than this, people born with PKU start experiencing issues. If you are looking for a clinic near you that treats PKU you should be able to use the 'clinic finder' link on this website, or go to macpad.org and under the tab that says 'links' click 'clinics.' Otherwise let us know where you live, and I am sure someone here will be able to help you find a clinic near you.
Please let me know if there is anything I can do to help you.