Thank you for this additional information.
As neither are up to date with their parasite prevention, and worms can present in this manner, the first thing I would do would be to have them treated. You can purchase a broad acting wormer such as Panacur online or from a pet shop or vet clinic. Adult dogs should be wormed every 3 months while puppies need to be wormed more regularly than this.
Worms are a common cause of vomiting, diarrhoea and blood in the stool.
There are, of course, other possible explanations for their symptoms including an infection, a reaction to the chicken bones, an unseen toxin ingestion etc.
Going forward, I would advise against feeding any bones.
The main thing is that both dogs remain active and alert. They should have pink and wet gums and should not be straining to pass poo, panting or unsettled.
You can start them on a probiotic anti diarrhoea paste such as Protxein Prokolin. This does not require prescription and is given daily for 3 days.
I would also start a bland diet of boiled white chicken and rice that is given littler and often for 2-3 days to rest their stomachs.
You should find that they improve shortly, over a matter of 1-2 days. If this is not the case or they seem any worse, a vet visit is best. The vet will examine them and may advise e.g. a stool analysis.