Help! Flickering Shadows

I’m trying to render this shot but the shadows keep dancing erratically on the character’s face. Granted, the lighting is a little dim but other objects in the scene are not having this issue. I have this up to 864 samples. I’m zoomed in here to show the detail but it’s still noticeable with the 100% zoom.

Any help would be appreciated. I’ve tried various settings, but nothing seems to work. Is there any other solution besides changing the lighting or cranking the samples up to 20,000?

Thanks!