I have a lot of anxiety around work and my IC.  It seems my symptoms are always worse on days I work and travel to work.  I do a little meditation in the morning with some positive affirmations or mantras as well as deep breathing exercises.  I also try to eat as cleanly as possible and drink only water so I know that it isn't what I'm eating and just reaffirms the anxiety-induced heightened symptoms so I know what I'm dealing with.  Hope this helps :)

It can absolutely be emotional die-off, even if it seems too strong to be "just that."
It can also reflect conscious/subconscious fears around working -- very natural concerns -- what if I can't find a bathroom?, how will I make it thru the day?, etc.  These fears create stress which creates different chemical changes in your body that can create anxiety or worsen the die-off anxiety already going on.
I'll try to think of more coping strategies, but here's one: Matia said an excellent thing for anxiety is putting a little lavender essential oil right between the breasts.  I've done it a couple times... I think it worked unless it also just went away on its own.
You can also sit quietly, in or out of meditation, and ask yourself "Why am I afraid?" or "What's going on here?" and see what answers/images come up.