I woke up this morning and felt the urge to go but it turned out to be not very pleasant. And now I'm worried because the pain down there is worse than it has been and it feels like it did again back when I had my fissure. Is it possible that I re-tore? Or am I just being paranoid.

Hi Tim,
It is very soon after your surgery so it is likely the diarrhea has just caused a lot of irritation both to the fissure and to the incision. Try not to panic, just keep on focusing your thoughts on healing and recovery, following good postoperative care and a safe diet. There isn't any reason to think about re-tears right now, so soon after your surgery.
Best wishes for a full and speedy recovery!

I second that - my surgeon said that when you have diarrhea you have more unprocessed bile etc in your stool and therefore it will irritate the fissure and the incision which are still healing. And in my experience this irritation will last for quite some time after the BM, so just try to relax and not worry about it too much. We're all just so attuned to every little feeling down there after what we've been through, and so anxious that the surgery will be the end of the problems. Remember that you need time to recover and take it easy on yourself. There is every chance that you will heal well.