vomiting

my cat is vomiting dry cat food sometimes mixed with feathers and or mouse fur this morning she also vomited a bit of foam this morning.
she is also skinny but that might be the heat cuz my sisters cat is skinny aswel.
does anyone know wut this is, or wut i can do about it

take any vomiting seriously ... how many times today more than two and I would be contacting the er vet

thanx i guess i wil go to the vet with her than