If you are taking certain meds, yes you can have the issue suddenly, along with GI issues like Gastroparesis, because you never know when it will flare. Last one drove my BP to heart attack level and sent me to the ER. 2 months to get it under control. The other half of GP is Constipation. So you lose no matter what, it’s a delicate balancing act.
All Diabetes meds have TONS of GI issues. That flu shot you got could also be the cause.
That's another reason for following the "Eat to Live" regimen (Dr. Joel Fuhrman). Basically a "greens and beans" diet. I've strayed from it, and my blood sugar has risen as a result.
Anyhow, the point I'm trying to make is if you follow the regimen, GI issues will disappear.
I've been type II for 3 years now, and I'm controlling it with diet and exercise...no meds.