My sister and I have had great results with the black cohosh. It knocks those hot flashes right out of the park.
Are you taking any medications for any other unrelated medical issues? Some meds can cause hot flashes too.
If your ovaries were removed five years ago, that put you into "instant" menopause, assuming you were premenopausal at the time of your surgery. If you took hormone replacement therapy after your surgery, that would have put off the inevitable until such time as you discontinued the hormones or the dosage was reduced enough to allow menopause symptoms to break through. I've noticed myself that especially at times of stress the hot flashes can tend to recur.
If your hysterectomy was for benign reasons [not cancer] and you have no history of breast cancer or family history of breast or gynecologic cancers, your doctor may agree to a relatively short course of hormone replacement therapy for your severe symptoms. If you do not want ot take hormones, note that some women have gotten relief from other medications, such as Effexor, or alternative treatments such as black cohosh [an herb].
I hope you find a solution. It sounds pretty uncomfortable.