During the Middle Ages and the Renaissance, most people either grew there own medicinal plants or visited the local apothecary for ease of pain and other complaints. In large urban centers there were physicians who would treat the sick and write prescriptions for medicine which would be taken to an apothecary to be filled. In poorer or more rural areas it was more likely that people would go directly to the apothecary for treatment as well as medicines. An apothecary would mix remedies using minerals, plants and animal parts to create their recipes. Many of the spices that are used solely in cooking today were important ingredients for healing during earlier times. An apothecary normally had a garden in which would be grown medicinal plants, but exotic plants were also imported from far away lands. One example that may still be familiar today is cloves. The last time you needed a tooth filled or extracted, the dentist may have placed a swab that tasted very strongly of cloves next to your gum to numb the area before injecting something to numb your entire mouth.
Midwives were primarily the ones that women turned to for assistance during childbirth. Originally men were banned from being present at a birth, so the only option was a woman. midwives did not receive any formal training, but sometimes a woman would become better at her calling and through word of mouth more people would come to her for help. These women would teach others and an apprentice type arrangement developed. At the same time physicians (men) began to receive education at the universities and their status was higher than the local midwives. It is felt that men still were reluctant to be involved in childbirth but the Catholic Church became more involved in the control of midwives. In an effort to control the lives and fertility of women, Religious leaders sought to control childbirth practices and many midwives found themselves in a precarious position. Midwives who would not be controlled by the Church could find themselves accused of witchcraft. It was at this time that physicians took a more active role in childbirth, but the practice of midwifery survives to this day.
In general a surgeon was an untrained person who learned on the job, or from someone else. They were responsible for removing limbs as well as teeth and were also who you went to for a haircut. There was no understanding of what caused infection in a wound, any instruments used were guaranteed to not be sterile and using their services was likely to result in an unhappy outcome for the patient. There are stories of barbers pulling teeth as recently as the frontier of the American west.
It was believed that "bad blood" was a common cause of everything from headaches to infection, and the cure was to remove some. Leeches were used for this purpose. The bite of a leech causes blood to flow freely from the wound, as anyone who has ever picked up one of them in a pond or brook can tell you. A Leech was a person who kept leeches for medicinal purposes.
Beginning in the Renaissance, Men were trained as physicians at universities of the time. This raised the status of physicians above that of apothecaries, surgeons and leeches. Most medical books available at the time were written in Latin so that people who only read in the vernacular would be unable to use them. There is also some thought that physicians wrote prescriptions but did not fill them because selling medications might lower their status. The education of physicians was much different than today, they were educated in astrology and philosophy more than actual, physical ailments.