When I was translating it I was also confused. My only source is a more experienced translator than me, who lives in Japan. Relaying the response when I asked him: "What it actually means is: 'I'm terribly stressed over not being to produce any results despite all of the efforts.'. 胃 is usually a metaphor (an old one) for accumulating wealth, and 胃に穴が 空く means no money were accumulated no matter how much come in."