I spoke to the breeder and she said I should get her checked out to be safe so that is my plan. I have never had a female so this is all new to me and this might be a dumb question but where do they bleed from when in heat?

My 7 month old female Ripley might be going into heat. Her appetite seems less, she is jumpy and more aggressive when interacting with male dogs which is unlike her. For the past 2 days she has had diarrhea and today there seems to be a little bit of blood in it. Is this just another sign she is going into heat? Or should I take her to the vet?