poor anxiety habit causing pain - any advice on stopping it?

I'll just get right into it, but ive developed a habit of repetively sucking my stomach in- not because of any eating disorder or body image thing, but I think due to my anxiety and poor habits that come from that (I honestly dont even know why im doing it I just know it has to do with my anxiety disorder) and i kind of did expect this to happen but now I've been having stomach pain so im just wondering what kind of advice could be given to help me move away from this habit? It's a twitchy repetitive kind of body movement so is there something else i could train my body to do to get my body moving similarly that won't be painful? Again this isnt because of body image or anything like that its just a poor habit. And disclaimer I do have an appointment with my therapist in a few days i just would like some ideas before then. Thank you to anyone who can help out