What Causes Sudden Dizzy Sensation While Treating MS, Lupus And Fibromyalgia?

Hi. My name is Elsie. I am 63. I was sitting at my computer and I suddenly had a strange sensation right around the sternum. It was like a black pit forming there and at the same time, I felt very weak and faint (for lack of a better word), head, arms, legs and head falling into this black pit. I did not pass out I do have a diagnosis of Lupus, MS and Fibromyagia and I am overweight (5 4 and 218). I am not sedentary as I keep my own house, babysit 2 babies and walk my dog 2x day. haven t taken any meds this morning (i take several): hydrocodone, plaquenil, azathrioprine, gabapentin,