Sorry my son is always crying at school and causing such a disturbance all the time.
Sorry my son is such a nuissance being upset and crying like he does at school.
ーSorry my son is always crying at school and causing such a disturbance all the time.
「息子がいつも学校で泣いて騒動を起こしてすみません」
to cry at school で「学校で泣く」
to cause such a disturbance で「ひどい騒ぎを起こす・大騒ぎする」
all the time で「いつも」
ーSorry my son is such a nuisance being upset and crying like he does at school.
「息子が学校で取り乱して泣いて、ひどい厄介者ですみません」
nuisance で「厄介者・うるさい人」
upset で「取り乱して・憤慨して」
ご参考まで！
カナダ 
