That is what makes us special, we are more attuned to the suffering of others, we have lived through it and survived, we have also gone through hell and back so we know intimately how lost kids can be when no one is listening...
I was the same kid as you, constantly running to the bathroom, doubled over in cramps, crawling to the bathroom in the middle of the night, moaning in pain with no one to listen or help.
They said that is was psychosomatic, that I was an attention-seeker, that I was making it up (bleeding from the rectum?), they hospitalized me 6xs with such severe bleeding that I needed to be transfused.
Yet, no one took it seriously.
I made feeble attempts to tell them but I was mocked by everyone. Ignored, told to buck-up and take it.
I was a lock-in for years, starving myself to be able to go to school or I would not survive classes (I still do it today or I will not survive the 1.5hr subway trip to school each way).
So, I put myself out there and tell the kids that nothing is more painful than a painful secret. That the enemy of depression is compassion and shared fears.
I tell them to talk...to anyone, a friend, a doctor, a family member but to not suffer in silence.
I told the story of the red nose to a friend, at dinner, and she and her husband broke down...Their daughter's best friend's boyfriend had just committed suicide the previous week...hung himself.
Her daughter was at a loss to understand, the parents too. He was 21. NO one saw a thing, no one expected it. He was so joyful and friendly. So full of life...until he wasn't.
So please talk to your kids, sit them down, make them bring home their friends for dinner (not as the main course!) and talk.