What Causes Vaginal Bleeding During Premasturbation Intercourse?

I had a hysterectomy 6 yrs ago. Average sex with husband 2 times a week. Last night for the 1st time I started bleeding during pre - masturbation intercourse with finger penetration assistance from my husband and we got a little rough duration about 30 minutes. He keeps his nails well manicured and lubrication is not an issue. This is really scary. Any suggestions on what could cause this and what I should do would be greatly appreciated. Thank You