flare-up

A sudden outbreak, outburst or eruption (originally of flame, but now used more generally of any violent activity or emotion).

But what I do think is that there's likely to be a regular flare-up soon. And how can one tell where that may end? If only I could get Ambrose to take me away somewhere! But he won't budge.

The disadvantage of the underfired grill is the potential for flareups, which can cause a burned spot or carbonization. Not only do these taste bad, but they are also carcinogenic.

A sudden intensification in activity.

An inflammation such as of tendons (tendonitis) or joints (osteoarthritis).

Although Crohn disease and ulcerative colitis are chronic, they are characterized by periods of remission that last for varying amounts of time, interrupted by flare-ups, when symptoms of the disease become more evident.