hugs hun,, sound a hard one,, sure your ds can have sweets,, if her eats his fruit and veg first!
i would try tough love,, throw away every single bad food you see,, and do this everytime some is in the house!
dont give ds ANY of these untill he is eating a proper diet,, not one!
he may not give in for a day or two,, but tough love is what it needs,, he will soon eat