Sorry about above premature e*********n.
Methotrexate by mouth or injection works about 100% of the time in the treatment of psoriatic arthritis, usually within 2-3 weeks. There is some risk, but treatment should be instituted and supervised by a rheumatologist. If you really want to play, see the rheumatologist!
If you want to screw around with all kinds of folk crap, you can try all of the aforementioned remedies. All of the anti-inflammatory drugs, steroidal and non-steroidals, also have side affects and little results in psoriatic arthritis. It can also eventuallyburn out.