Joint pain but no swelling

Hello: I have had severe joint pain and intermittant swelling in my hands, wrists, elbows, neck, shoulders, knees and feet for 3 months. I had a very hard knot develope on my wrist. My mouth is extremely dry. My joints pop and crack. I have had a low grade fever for 3 months. BUT MY EXTENSIVE BLOOD TEST RESULTS ALWAYS COME BACK NEGATIVE! My rheumatologist has not seen the swelling, and cannot diagnose me. What other tests can be performed to diagnose ra? Can a CT scan show that you have ra? Can an ultrasound? I cannot have a MRI due to interstem device implant. Can the doctor have lab testing done on synovial fluid? Will this show ra when blood work does not? I am desparate for an answer and help. I am a very active person, work full time and college full time, and am a single parent. This has stopped my life. I thank you in advance for an answer. Sincerely, Wendi Foster