Your plant will need some nutrients by the end on the 3rd or 4th week. You can use a fertilizer that is for tomatoes since they have similar needs to cannabis. You can also use miracle grow if that is all you have available. There are numerous things most people have laying around their house that are great fertilizers. Banana peels, used coffee grounds, egg shells, etc. Manure (especially Rabbit) is a great fertilizer if you have access to it. She will probably be ok for another week without food but she will be hungry soon. Good luck with your grow.