Does anyone here suffer with TMJ problems? What do you do that works when a flare up is super painful?

They recommend eating a softer diet. Taking painkillers (anti-inflammatory so long as you have no conditions), talking or opening the mouth less. Alternating between cold and warm compresses.
Resting.
Then booking an appointment with your dentist.

They may be able to help with a oral massage, offer you a splint, or recommend you see a specialist.