I have had frequent urination with upper back pain and very bad fatigue. Is this something severe?

Could be, see a Dr. Symptoms could be from pyelonephritis or reflux of urine from bladder to kidney or combination of both. Certainly deserves wokup by a urologist or nephrologist. A simple urinalysis from your primary medical care provider would make a good start.
See below. Frequency can be do to a urinary tract infection treated with antibiotics. Can be a sign of kidney problems see your doc to get lab work and a phy exam. What medications are you on. Are you on diuretics can be a sign of diabetes mellitus and hi blood glucose. Also diabetes insipitus can cause polyuria.