osteoarthritis diagnosis as not "ticking all the boxes"

I've had plaque psoriasis for about 25 years (now aged 44). Last year I had blood tests as was feeling so tired. I was diagnosed with vitamin D deficiency and given a "loading dose" supplement for a month. At the end of that month overnight I developed pain in my knees. I also now get pains in my fingers, toes and back. After more blood tests, X-rays, scans I was sent to the rheumatologist who has diagnosed osteoarthritis as I'm "not ticking all the boxes for PSA" and has discharged me to my GP. I've seen the letter from the rheumatologist which says I'm hlab27 positive. I've written asking for more information about this. Am in constant at the minute. My physio has said I've a flared knee. Just wonder if anyone else had had vitamin d deficiency before diagnosis or was misdiagnosed with osteoarthritis? Thank you