What Causes Intermittent Dizziness And Nausea?

I have been having dizziness and nausea on and off for about 9 months now, I have also experienced joint pain on arms, knees an pain along my spine and on my big toe! I have also been getting itchy nipples with milky discharge! I get swelling on my hands and feet and have difficulty concentrating, what might it be? I was sent to a specialist cUse once I had low platelet count but they weren t able to figure out why and the second test came out normal