Yes, flares can last for a little while sometimes. What happens with me is I get something like 2 days genuine 'flare-up' when guts are a real mess indeed, then it calms down, but followed by a period (a few days to sometimes a couple of weeks or more) when my gut is okay...ish but not great, with ups and downs and feeling a bit sensitive.
The only thing I can do to hopefully ease it is to really watch what I eat, and eat my real safe foods, not even think of stepping outside that or experimenting at all with anything which might have caused irritation in the past (that can be healthy food like steamed celery or brown rice or something), plus do my best to get enough sleep.
It does usually calm down in my own case but I'm never sure if it's my strategies, or just the unpredictable nature of IBS itself that brings about any change. But at least the diet strictness helps to manage symptoms.