Hi Roo - only just saw this.
I would bet my bottom dollar it was the steroids that caused the mood swings and I cant fathom why they didn't give him an IM Depo-Medrone 120mg instead of oral steroids, which is sometimes given to tide people over until their next infusion is due. This is something I strongly suggest you discuss with the Consultant.
As for Sulfasalazine versus Hydroxychloroquine, its swings and roundabouts in terms of side effects. You can take both as part of a combined regimen and they can be taken with MTX too. Hydroxychloroquine is only taken 5 days per week so most people opt to have Saturdays and Sundays off.
If you continue to run into problems or fail to achieve disease control with the next drug regimen, biologic therapy will have to be considered. In the meantime I cannot recommend the IM Depo-Medrone highly enough. Of course the decision is one that your son and his Cons must reach together.
Please keep us updated.