Hair started falling out quickly for no reason.

So for context I'm 18 and have fine, wavy hair that goes down to my shoulders, and I've had it for about 2 years now. For all that time my hair has been pretty normal loss wise, then randomly over the course of a week my hair started falling out and tangling much more often, I haven't made any changes to my lifestyle too, I thought it might be split ends so I had a haircut but that hasn't made much of an impact, its been like this for about a month now, any ideas why it's happening and how to stop it?