The purpose of this study is see if Transcutaneous Electrical Nerve Stimulator (TENS) units help decrease endometriosis flare pain. TENS units have a 510K and are intended for relief of pain associated with sore or aching muscles of the lower back, arms, or legs due to strain from exercise or normal household and work activities. Participants will complete surveys, record pain, medication use and bleeding in an online diary during endometriosis flare ups for 3 months without using the TENS unit. After the first 3 month period of time, a TENS unit will be given to participants to wear and again, record pain, medication use and bleeding in the online diary during endometriosis flare ups for and additional 3 months while using the TENS unit.