I had those same issues with first numbness, then progressing to sore joints, in the fingers and toes. Then it progressed to sore joints around the body.
It seems that the flare-ups heighten pain sensitivity in the peripheral nerves in addition to the gut problems. My whole body feels 'raw' when it happens.
I have no idea on what the pathology is, but I expect it has a genetic component. It seems that my gut has issues with the self-regulation of certain neurotransmitters.
Over the past decade or more, I've tried nearly all of the other treatments for IBS and none of them work. The peppermint oil capsules were the worse. It was a complete waste of time and you walk around with the smell of toothpaste, at least that's how it felt to me.
You can refer back to some credible information for patients like this here from the NHS -
https://www.nhs.uk/conditions/irritable-bowel-syndrome-ibs/f...
Amitriptyline is clearly a treatment option for IBS there. Insist on it and your doctor should have no reason to deny it to you unless you have a contraindication.
If you're not in the UK, then there are other sources like this -
https://www.mayoclinic.org/medical-professionals/digestive-d...
Key takeaway from that article -
>In one trial, nearly 70 percent of patients receiving 10 mg of amitriptyline experienced a complete loss of IBS symptoms compared with 28 percent of those on placebo.
I guess I'm lucky and in that 70%. I hope you are as well. It's such a big effect on my health, I wish I knew how to deal with it sooner.