Thanks for query,
It seems that due to some infection on scalp
spreaded all over scalp in the form of small abscesses causing pain and foul odour.
Remove his hairs and clean with betadine
lotion thoroughly and apply betadene cream.
Do the dressing regularly.
Take care that there is no flies touching scalp,if they put eggs on it will give big problem.
Take long antibiotic course.
Ok and bye.