What Causes Cold And Numb Toe With History Of Lupus?

I was diagnosed with bilateral vascular systemic lupus. I had not had an SLE flare in over 25 years and was off of prednisone for several years. My ankle and feet started hurting and swollen and could not stand because of sensitivity. Now under control with plaquenil. But my right toe has started to feel cold like water runs through it. I touch it and it feels somewhat numb. Is this related to the diagnosis?