LOGIN PATIENT PORTAL. SAME-DAY APPOINTMENTS. Center for Internal Medicine, PA. Medical Center: 8265 Fredericskburg Rd. San Antonio, TX 78248 . Phone: (210) 200-8798 | Fax: (877) 904-3712. CENTER FOR INTERNAL MEDICINE SPECIALIZES IN THE CARE OF ADULT WOMEN AND MEN ABOVE AGE 15. A GENERAL INTERNISTS IS A PHYSICIAN WHO SPECIALIZES IN INTERNAL ....