Medical gaslighting??

Back story; I was diagnosed with Colitis in 2017, I am prescribed Mesalazine granules and suppositories, since going Vegan in 2020 (dairy was a huge trigger) I've been mostly in remission, and hardly ever used the suppositories. I could eat and drink whatever I wanted, alcohol, caffeine, greasy food, high fibre veg, large meals, you name it!
I had a big-ish flare up towards the end of 2024 where I had to have almost 3 weeks off work, which I think was stress induced. Since then I've been getting small flares which I could mostly manage through diet restriction and nightly suppositories for a couple of weeks.
However, the last 6 months or so have been a constant battle, within a week of stopping regular use of the suppositories and starting to introduce "healthy" foods I get the mucus, the dragging feeling low in my gut, the blood, then the cramps, fatigue, loss of appetite, joint pain, you know how it goes. I hadn't bothered my GP because to be honest he wasn't interested and was reluctant to make any referrals, the IBD team at the hospital were non-existent unless you had a severe case, which I didn't. So I continued with little to no support.
I just moved to new area under a different health board and so went to see my new GP who referred me to the local Gastro team for review, along with Rheumatology and a dietitian. I was so relieved to feel listened to that I cried, finally someone was taking me seriously.
I had my gastroenterology appointment yesterday and the Dr that I saw basically told me I have IBS and should consider mental health support. He didn't listen to any of my concerns about my symptoms or weight loss, and refused my request for a medication review even though it obviously isn't working as well as it once once despite no other lifestyle changes. Even if IBS is a factor surely the other symptoms require taking seriously?
How do I deal with this? After such a positive start it was a massive kick in the teeth to be dismissed like that. I feel like I'm going crazy! I'm at the point where I feel like I just allow the flare to come rather than battle it just to prove a point that I'm not lying!
I'm also thinking of starting to look into non-medical treatments and alternative therapies. If anyone has any experience with these please do let me know your findings and results.
Any advice or even just reassurance would be greatly received!