Plaquenil takes several weeks to build up in the system. So this may be why your reaction didn't occur immediately. Likewise, the half life is 60-90 days, so your rash may be slow to dissipate. Hopefully because you were on it such a short time and may not have even accumulated to a full blood level, it will leave your system a little faster.

It's not a frequent side effect from the many people on the Sjogren's board I know taking it, but I do know of several who have had the same reaction.