Phase 2 evaluation Pre-Employment Medical Examination (PEME)
You need a medical certificate as part of the requirements for obtaining an OEC certificate. This involves a physical examination. This is stipulated in POEA Memorandum Circular No. 08 of 2018, section IV.
Exemptions
You don't need a medical exam if you had one as part of the process of applying for a visa. From section IV, paragraph 2:
A Direct-Hire OFW may be exempted from PEME if the worker has undergone a medical examination as a requirement for issuance of visa be the country of destination.
Health facilities
You must go to a "Medical Clinic accredited by the Department of Health (DOH)." See Health facilities document for a list of accredited facilities.