Comparing Adjuvant Treatments for High Tone Pelvic Floor Dysfunction

Inclusion Criteria: * Self-reported moderate to severe chronic pelvic pain for \>6 months duration at time of screening visit. Moderate to severe chronic pain is defined as \>4 on 0-10 (worst daily pain) for \>14 days per month. Pelvic pain is defined as pain perceived to be located in the anatomic pelvis. * Diagnosis of high tone pelvic floor dysfunction (HTPFD), defined as \>12/60 summative pelvic floor tenderness score on standardized pelvic examination by chronic pelvic pain specialist (MD or NP) within the past year * Referred to pelvic floor physical therapy (PFPT) by their chronic pelvic pain specialist for management of HTPFD * Willing to undergo a 12-session course of PFPT for HTPFD, including internal/vaginal tissue manipulation per standardized protocol * Willing to delay start of PFPT until Phase 2 of the trial * Willing to be randomized to either daily use of cyclobenzaprine or use of vibrating pelvic floor muscle massage wand for total of 18 weeks * Willing to undergo standardized pelvic floor myofascial exam three times over the study period (baseline, end of Phase 1, end of Phase 2) * Willing to undergo quantitative sensory testing (QST) two times over the study period (baseline, end of Phase 1) * Willing to undergo blood draw two times over the study period (baseline, end of Phase 1) * Ability to read and speak English to allow for written informed consent, phenotyping, and patient-reported outcome measures * No plans for pregnancy within the next 12 months Exclusion Criteria: * Hypersensitivity or allergy to cyclobenzaprine or any component of cyclobenzaprine * Underwent PFPT within 6 months of screening date * Pregnancy at any point during study period (self-reported home urine pregnancy test or serum b-Hcg test, positive urine pregnancy test at baseline, post-Phase 1, or post-Phase 2 study visits). * Currently breastfeeding at time of screening visit * Scheduled for or are planning moderate/major gynecologic surgery (including hysterectomy, excision of endometriosis, ovarian cystectomy/oopherectomy, myomectomy) within the following 6 months of screening date * Current (at time of screening visit) diagnosis of postural orthostatic tachycardia syndrome * Current significant neurologic or musculoskeletal conditions that would preclude participation in PFPT (cerebral palsy, severe hip/back osteoarthritis that would prevent lithotomy position during sessions) * Unwilling to avoid or stop baseline use of cyclobenzaprine and other muscle relaxants (including methocarbamol, tizanidine, baclofen, carisoprodol, metaxalone) * Current use of tricyclic antidepressants * Current use of monoamine oxidase inhibitor * Current use of vaginally delivered benzodiazepine such as diazepam (more than once per month) and unwilling to stop use of vaginally delivered benzodiazepine for the duration of this study * Current diagnosis of hyperthyroidism * Current diagnosis of moderate or severe hepatic impairment * Myocardial infarction within prior 12 months * Current diagnosis of congestive heart failure * Current cardiac pacemaker in place * Current diagnosis of closed angle glaucoma * Current major psychiatric condition (including psychosis or suicidal ideation within past year)