IBS for over 10 years now

No, you are not a hypochondriac! That is a silly form of medical gaslighting for anyone to accuse you of that!
What you describe is typically what many people with IBS go through.
Unfortunately once all the obvious clinical investigations come back "normal" and we get diagnosed with "IBS", the doctors seem to be stumped and not know what to do with us next. So we get sidelined.

I feel that definitely a doctor or good practitioner who focuses on "functional medicine" might be of some help to you. The good ones do seem to have a more lateral-thinking way when it comes to conditions like IBS, and you are treated more holistically.

There is a brain-gut anxiety loop that can cause a vicious cycle of negative feedback. Nope, IBS is not just in your head, but the brain and gut can have awful arguments. Sometimes it can be related to serotonin levels perhaps (I often wonder about that) And sometimes I feel it can be related to a form of PTSD, as memories of awful incidents or terrible flare ups can set off a dreadful anxiety loop, (which of course makes the IBS worse!) This can often be beyond our conscious control, and acts more like a scared wounded Creature inside us. That's what it feels like to me.

There is definitely something called "post infectious IBS" so if you could discuss that with your doctor or GI specialist you might get some answers. I am not sure how it works but it could be a severe disturbance in gut microbiota, where the bad bugs start to get the upper hand.

Maybe a probiotic such as Alflorex might help you? (I have heard positive things about it for IBS though not tried it myself I admit.) And I have also heard good things about the "Nerva" app for stress or anxiety related IBS.

I'm sorry that you're dealing with this and that your doctors don't take you seriously. IBS is definitely not just in your head. I was also diagnosed in my early 20s and told the same thing: that it was all due to stress. And while that might even be true, this information doesn't help at all.
Like you, I also have IBS-D and it's triggered by stress and anxiety. For me, I have found that trying to "talk myself out" of stress and anxiety only makes things worse. It's like whenever I try to suppress these thoughts and feelings, my body reacts even more. I've done the Nerva program and am currently doing EFT tapping (for free on YouTube, if you're interested), and both seem to work more on the unconscious side of things. For me, it's the only thing that helps, and these techniques prevent me from spiraling when I get a flare.
Also, this is just my experience, but if something doesn't feel good, it's unlikely to help me. So if the treadmill makes you feel depressed, maybe try something else, like going for a short walk outside every day? I find that being outside really helps, especially when I'm feeling anxious.
For me, eating a gluten-free diet with lots of protein also helps, but that's different for everyone.
As for the infection: I've heard from people who had undiagnosed infections for a long time, so if you haven't had a stool test after your food poisoning, it might be helpful to get one. But I also agree with the comment above that a functional doctor might be able to help even more, I've heard that they do more in-depth testing of the gut microbiome.
I hope this helps and that you'll start feeling better soon.
Karina (team member)

when you said "everyone says is "normal" when I in fact know it is not." -- I totally agree, it's not normal, IBS symptoms are not normal

Besides counseling, I tried EMRD and that has really helped me