Anya, your story sounds just like mine! Undifferentiated spon., sulfasalazine, swollen knees. I'm young just like you too!
How much has the SSZ been helping you? My rheumatologist said that it would only help peripheral joints but likely not my spine. I've not been on it very long and not the full 2000mg yet, but I already have side effects (headache, nausea, diarrhea, bad sunburns). Just looking into what results I might expect while on it...

Liza, 21

Dealing with undifferentiated spondyloarthropathy and taking each day as it comes.