Rheumatoid Arthritis Support Group
Rheumatoid arthritis is a chronic, inflammatory, multisystem, autoimmune disorder. It is a disabling and painful condition which can lead to substantial loss of mobility due to pain and joint destruction. The disease is also systemic in that it often also affects many extra-articular tissues throughout the body including the skin, blood vessels, heart, lungs, and...
Although it is comfortable to have a nice, tidy diagnosis, he may be doing you a favor by keeping it vague. For example, Achilles tendon involvement is very common in psoriatic arthritis. (I don't know if he is correct about RA not affecting it. Maybe it doesn't in the textbooks.) By keeping you in a grey area, the door is open to try a biologic which is approved for RA but not PsA, as well as on that is only approved for RA. There are a lot of autoimmune diseases out there.
Linda