When my ibs is at its worse ill get symtons of anxiety(fight or flight) without all the mental workup. Then my chest gets tight and its harder to take a deep belly breath. Then your having breathings issues. Try humming. Hum at a low tone inbetween breaths for as long as you can. (Like on the drive to work). That stimulates the vagus nerve around your vocal cords which calms down your nervous system. Allowing your chest to relax making breathing easier.