Could Severe Back Pain Along With Dizzy Spells Be Due To Stress?

I am a healthy 26 year old female. I have been having extremely bad back pain for the last 2-3 days that has just spread to my pelvic area. I have been having dizzy spells along with nausea and tingling sensations in my legs. I have also been short of breath and catching myself holding my breath unconsciously to dull the back pain. My last period was abnormal in the sense that at first it was completely black, stopped, then came back as a normal period that lasted longer than usual (7-8 days) then turned brown the last day. Is this caused by stress or is it something that I should be concerned about and go talk to a doctor?