Sounds like he may have released some toxins during the flush that didn't get all out.
Is he drinking plenty of pure filtered water (at least 1/2 his body weight in ounces)?
Has he been eliminating well?
Would he possibly do an enema to help wash out any gunk that may still be hanging around in his colon?
Has he tried drinking a saltwater flush first thing in the morning - before ANYTHING else? (One quart *warm* filtered water with 2 level teaspoons of Sea Salt - drink as quickly as possible, stay near bathroom.)
If none of the above are working, see if he will flush again. Have him eat lightly the day before the flush (veggies, salads, fruits, no heavy starches) and drink the saltwater flush 1st thing the morning of the cleanse. This will help with clearing the colon out before the Liver Flush later. The Epsom Salts help, but the cleaner the colon the better.
Another question, especially if the above doesn't help - has he done a parasite cleanse?