I had the exact same issue. Tried like 3 times to submit a sample but was rejected due to having formed stool. I was sneeky though and saved one stool test kit till I went for my hydrogen breath test where I drank sorbitol and got the runs. I submitted that and it got accept muhahaha! (negative though)
Oct 10: DX proctitis (6cm of rectal ulceration)
Nov 10: DX IBS and cecum inflammation
Aug 12: DX Crohns? (mild ulcers on ileum)
Dec 12: DX Fructose + Sorbitol malabsorption
STATUS: Colon clear. Mild ulcers on terminal ileum
1g Pentasa supp (1 every night) + 3x1.5g Salofalk granules daily.