Welcome to our Arthritis Community. I am sorry to hear about your pain and the fact that you do not have a DX (Diagnosis). I know how frustrating - and even frightening that can be. My heart goes out to you.
I don't know what condition you may be experiencing. It doesn't sound like Arthritis - certainly not RA (Rheumatoid Arthritis).
Let's look a bit at your positive findings, the ANA and CRP. ANA test results are just one factor considered when a diagnosis is being formulated. ANA can be positive in patients who have various autoimmune diseases, but not only in autoimmune diseases. ANA (Antinuclear antibodies) can be found also in patients with infections, cancer, lung diseases, gastrointestinal diseases, hormonal diseases, blood diseases, skin diseases, and in elderly people or people with a family history of rheumatic disease. It may be elevated in ppl that such conditions as Lupus or Scleroderma. ANAs are actually found in about 5% of the normal population, too. So a positive ANA only tells a physician that something may be going on - it's not specific to one condition or disease.
A CRP (C-reactive protein) elevation is similar to ANA - it's a marker for inflammation in the body when elevated. Following a severe injury your ANA can rise - or with an infection.
It sounds like your PCP is following the right path to find a DX for you. Urology (for flank pain) and Cardiology (to evaluate your cardiovascular status) may be other specialties you'll want to consult.
That fact that a steroid provided relief would lead one to conclude that the steroid reduced the inflammation and thus reduced your pain. Now it's up to the specialists to determine what and where is the cause of your inflammation.
I encourage you to educate yourself. Read and research the tests that are being done - and know what the possibilities. You can than be a partner in your care - and better understand what's occurring in your body and make educated decisions and suggestions. You are your own best Health Care Advocate. Be assertive.
I'd also request a copy of all the related medical records - from each physician you consult. Don't forget the medical records from your PCP. The more you know - the better.
I wish I had better answers for you. I do suggest that you request comfort measures. Sleep is in important factor in health. If you physicians offer nothing than a discussion with your Pharmacist may be beneficial.
Please let us know how you are doing. I hope you'll soon have answers and be more comfortable. I'll look forward to hearing more from you.
Take Good Care of Yourself,