Yes I had serious tummy problems for many years. I always knew they were related to anxiety and fear because the connection was so clear. Every year when I went back to school I could barely eat for about 6-8 weeks. My stomach was too cramped up. Especially in the morning, which I've read is when the stress hormone cortisol is at its highest levels as well. I'd spend long periods in the bathroom with debilitating cramps as if my entire insides were spasming. I'd break out into shaking and cold sweats and it would just spasm again and again until I was just wrung out. Eating made me sick, and at the other end of the digestion process, just worsened the whole experience.
Also, I expected myself to soldier through this and not mention it to anyone. And oftentimes I would choose to push forward in situations that brought on the pain, but I never conquered it that way. It didn't make the pain go away or solve anything.
It happened less often in my 20's but still did happen. Yet, in my 20s I believe I began to be avoidant of situations that provoked this kind of pain. Say, new jobs or job searching or applying to grad school are just the sort of things that would provoke major pain, so I stayed in the same job for a decade. I took GREs and LSATs but couldn't bring myself to apply anywhere, etc.
But it has not happened at all since a friend of mine told me what she did. She said - she experienced such cramps and she asked her stomach to tell her what the concern was. She sat with herself and patiently directed her attention in a receptive way to this area of the body and listened to all it had to say. And the cramps went away. Now I do that, too.
See, in the past, I was punishing myself for what I had to say (and what my body had to say) - I was acting like my N parent to myself. I was soldiering on because I wasn't allowed to have fear, vulnerability, anxiousness - that sort of thing infuriated my dad because it was needy. So I ignored and punished that neediness in myself, and hated myself for it and the pain continued.
I still have anxiety issues, but not to the extent of that incredible physical pain. I still have a lot to learn about the proper way to interact with my own body and self and others too, but I do yoga and study yoga philosophy and feel it helps very much because it is a practice of actions that are kind and wise and friendly with yourself. It's a practical path of action on these issues.