What is exactly is he anxious about? Can he articulate it?
My daughter has had a LOT of trouble with anxiety which is entirely related to medical procedures and severe chronic pain.
For us, what has been most helpful has been seeing a psychologist regularly. She didn't want to go, and really fought it but now is the first one to say that it really changed her life.
In her case, the anxiety revolves around pain - if it is really bad, when will it get better/is it going to get better/"I can't deal with it anymore" kind of stuff. If the pain is a bit better or under control, "when will it come back" is the big issue. She is able to keep herself distracted during the day and so it's at night when it's a big problem.
For her, we have found some tools that help. At night, she listens to audiobooks while falling asleep so she doesn't focus on the pain or the anxiety that comes with it. In general, distraction is very helpful and yes, that sometimes means she watches a lot of TV or uses her computer way past bedtime.
She has a couple of apps that she likes - iSleepEasy has guided meditations that are appropriate for teens and older kids (recommended by the pain center at Boston Children's). It also has nature sounds which she likes to listen to when falling asleep.
Then there is an app for younger kids called Comfort Kit. It has a lot of tools - the child can choose how they feel ("worried" or "angry" or "sad") and then what to do about it - there are a bunch of choices (guided imagery, belly breathing - that kind of stuff).
I would say the apps are most helpful once the kiddo has learned these skills with a psychologist. But if you can't get to a psychologist, you could work with him.
When she is in a lot of pain, it helps her to try and do something - so distracting herself by doing a puzzle, or playing a game or doing her PT exercises/stretching. If she is in too much pain to do something active or can't concentrate enough for a game or puzzle, then TV honestly works best.
We also use a lot of ice and heat for the pain. A TENS unit might help too. Has he been given an IBS med? We use Levsin for belly pain and that really helps.
When she was younger and still in school, unless the pain was very severe she would try to go to school. School is distracting - if they're home, they just focus on the pain. That meant that sometimes she would go to school and not attend all her classes - she'd go to the nurse for some, or she'd call me at lunch time asking to go home, but she tried to be in school as much as possible. Being with her friends, having to concentrate on school work - all that took her mind away from the pain (unless it was really severe).
For kids with chronic pain syndromes (and I'm not necessarily saying your son has one), going to school and keeping life as normal as possible is very important. That means doing stuff even when the child is in pain - sometimes in a lot of pain. It is REALLY tough and that's why there are inpatient pain programs that teach kids to push through the pain - it's often not something they can do on their own, if the pain is very severe.
In a pain syndrome, what happens is essentially that they have over-active nerves that keep sending pain signals long after the initial trigger for the pain (inflammation, a virus, an injury) has healed or is gone. In my daughter's case, she lived with uncontrolled joint inflammation for so many years that her nerves just got used to sending those pain signals. So now when there is even just a little inflammation, she feels a LOT of pain. That's why these pain syndromes are sometimes called "Amplified pain syndrome" or something like that.
For abdominal pain, the equivalent is called visceral hyperalgesia which is essentially amplified pain of the belly/stomach.
But anyway, 9 times out of 10, my daughter will be happy she pushed herself to go see her friends or go babysit or get out of house. Sometimes she'll go and regret it - that happens too. But most of the time, keeping things as normal as possible helps. It is REALLY hard for her to sometimes make herself go - sometimes I drag her to the gym to swim and she is so grumpy on the way there. But once she's in the water, she's happy and her pain goes down.
All this does apply to a chronic inflammatory illness like IBD with one caveat - kids with IBD do need to rest sometimes and listen to their bodies. They become anemic, they get dehydrated so it's not completely the same as a chronic pain syndrome, where they essentially have to ignore their bodies.
It is especially tricky when a kiddo has BOTH issues - a pain syndrome and an inflammatory illness because you have to treat them differently. In an active arthritis flare, she can't push herself too hard. But in an amplified pain flare, she does have to push past the pain sometimes.
But the bottom line is, what helps with anxiety is keeping them busy, involved in school, extracurriculars and when they're home - not focused on the pain.
It also helps my daughter's to be reminded of the plan - these are the things we are doing to change her pain - changing meds, procedures, PT etc. In your son's case, you are trying to get a dx, so remind him that he's having scopes and if those don't find anything, then you will keep looking.
Sorry that this is so long - I know I'm rambling now. I'll tag some other parents who may have ideas: my little penguin, crohnsinct
