Sudden aim loss, help!

Over the last few months I've been managing to get 40%+ accuracy with Tracer, sometimes much higher. I figured I'd finally settled into her and I'd only improve from there.

However, for the last week, I can barely reach mid-20s. My damage and elim numbers have gone to shit because of it. No settings have been changed.

What the hell is going on?

I know it's a vague question, but is there anything practical I can do to start rectifying this? I've been practicing aim in custom games all week and it's not helping.