Hello and welcome Captain ca-ca,
I personally think it does sound like the UC is acting up. Not everyone has great results with Canasa and there are other meds you can try, Rowasa is an enema that delivers 4000mg of mesalamine to the rectum and left side, that may help you more if the Canasa isn't reaching the inflammed area. You may also try something with some cortisone. Cortifoam is great for rectal inflammation. Chances are, your mildly inflamed above the area that Canasa treats. That or, you're not responding well to mesalamine treatments. If the case is the latter, you would benefit from trying cortisone. If it's the earlier, you may need an enema to reach further into the colon.
Did the GI say where the colitis was active?
The max dose of Asacol is 12 400mg pills a day. You could speak to your GI about
going up to the max but that will not help if the inflammation is close to the rectum because it won't treat that area, that really needs topical treatment. I wouldn't worry too much about
the mesalamine rectal meds, they are pretty safe, even for longterm use. Safer than inflammation over a long period of time.
I hope you're able to get this under control quickly.
Another thing that can cause discomfort and bleeding would be fissures. I've had them and they are terrible uncomfortable but I think your GI would have noticed if you had something like that going on. Plus, it's not just uncomfortable, it's awfully painful, like cry when you feel the urge to go because you fear the pain.
Is the blood bright red? On the tp or in the bowl? It sounds typical or mild rectal inflammation. I had proctitis when I was first diagnosed and my only symptom was blood on the paper.