Why is my hair falling out, PLEASE help?!!?

Okay so, I'm gonna be completely honest. It's summer, and I've been SUPER lazy for the past 5-6 days. For 5-6 days, I haven't washed, brushed, or cared for my hair, and kept it tied in a bun (go ahead, call me gross and judge me). And I just took a shower and washed my hair, and while I was rinsing out the shampoo a knot in my hair just ripped off my head (I didn't even feel it). It was a hairball the size of a large pebble. And them some more of my hair fell out when I was brushing it :(. I'm seriously scared, am I loosing my hair?