SparksUC,
Glad your doc prescribed LDN for you.
Everyone's different in response time. For some it may take 1-2 weeks, for others a few months, it really depends on your body and how much "work" the LDN has to do.
But I can tell you that you will get better and faster results if you are on the SCD diet (specific carbohydrate diet), I don't know why, but it just seems so. Actually, it's probably because the things you are cutting out stress your gut so much that it prevents it from functioning properly, so when you cut out those things, it enables LDN to work better.
SCD is tough to do though. Maybe start cutting out dairy and wheat and see if that brings you more relief and better results?
As far the reactive arthritis, how long have you had that? It often comes with UC. And as Red informed me, it might actually be called Peripheral Arthritis.
Hope you start seeing improvement soon. Good luck.
Keep us apprised.