my 5 month old staffy girl is teething her mouth bleeding etc .could this be the reason for her bad breath? . she also hasnt eaten her dry mix could this because of pain as shes drooling over what im eating?.

My dog had terrible breath when he was teething. I remember coming onto this site for advice !.
Anyway, it turned out to be his puppy teeth which were causing the problem - try smelling one when it falls out !. I guess they, and the tissue in and around them goes a bit rotten. It was sorted out when I gave my boy lots of nice hard chews to help things along and to help his new ones break through.