I'm not a histology expert but I am sure that negative biopsies can't conclusively rule out IBD. My colon biopsies post-surgery were negative and yet I'd had Crohn's for 13 years by that point. Nobody can diagnose you over the net, but your symptoms and your elevated CRP definitely flag something more than IBS to me.
Good luck with your new doctors - I hope you find some answers.
Dx Crohn's in June 2000. (Yay )
Tried: 5-ASAs, azathioprine, 6MP, Remicade, methotrexate, Humira, diets.
1st surgery 20/2/13 - subtotal colectomy with end ileostomy.
2nd surgery 10/7/15 - ileorectal anastomosis. Stoma reversed and ileum connected to the rectum.
Current status: Chronic flare. Do I have any other kind?
Current meds: 50mg 6MP; Entyvio (started 3/11/16)