Why do i find blood in the back of my throat when brushing my teeth ?

I was brushing my teeth this morning and i was spitting out all of this blood. I thought it was my teeth at first, but i take really goooood care of my teeth. After I brushed my teeth I realized it was DEFINITELY NOT from my teeth or gums, its from the back of my throat. When I gently brushed the roof of my mouth near the back of my throat blood was on my toothbrush. I don't feel sick and my throat is barely sore. I don't have a cough. I'm very worried because when this happens and i spit, there's blood, small amounts, like red swirls. this has been happening for awhile. about one year ago i started nasal gargling daily with warm water and sea salt to clear allergens and pollution from my nasal pages. i believe that the blood was happening before i started this.