My dog is pooping out a brown jelly-like substance with some specks of blood?

Okay, I am super worried. The vet is closed already so I'm gonna take her tomorrow. My dog has been like this for 4 days straight & she kept me up ALL night taking her out every hour of the night. She poops out a jelly like substance that literally looks like egg whites but is brown. Today I discovered some red specks of blood on it. It's not a lot but she does go out a lot so it adds up. I did change her food to the wellness brand & I made her try the 3 types for allergies. The duck & rice and salmon & rice didn't cause this but the lamb & rice is triggering something & honestly this one she eats without a problem. She's been off of her other food for 5 months onto this brand but I haven't seen her devour her kibble like she has with the lamb & rice one. I've also been seeing her eat grass outside so can that be the problem. Please help I'm freaking out!