פירוש על עבודה זרה 55:6

There are two versions of what types of wounds should not be healed by a non-Jew. The first is the type of wound that may be healed on Shabbat—meaning a life-threatening one. The second is an internal wound.

Hand and foot wounds are considered serious wounds for which one may break Shabbat even though they are not internal wounds. According to the first version, one may not be healed by a non-Jew for them, but according to the second version, one may since they are not truly internal wounds.

If you have to ask the doctor about it, then you can transgress Shabbat to heal it.

Earlier we learned that one may break Shabbat in order to heal an inner wound. A burning fever is an inner wound. Inner begins anywhere from the lips and inward, although the next section seems to be unclear about whether this includes the gums and teeth.

Do pain in the gums and teeth count as internal wounds?
Abaye quotes a baraita saying that one should not rinse one’s teeth with vinegar on Shabbat, for this was a form of healing and healing is prohibited on Shabbat. [This is a topic we will not get into here, but will learn when we learn Tractate Shabbat. Healing is a big issue on Shabbat, and generally the rabbis did not allow it]. But this is only if one is “troubled.” If the pain is bad, it would seem that he would be allowed to rinse with vinegar. Thus, gums and teeth are internal wounds.
The Talmud rejects this—it could be that by the word “troubled” the Talmud means even a lot of pain. No matter what, one may not heal wounds in the mouth.

In this strange vignette, R. Yohanan goes to a female non-Jewish doctor. She heals him but he wonders what he will do on Shabbat. Rashi explains that he can’t come to her on Shabbat because he will be busy teaching. In any case, the story seems to prove that one can heal gum sores on Shabbat.

Scurvy is worse than regular sores on the gums because it can spread into one’s body. So one can cure scurvy, but we’re still not sure about regular sores.

This section is a little sugya about the symptom, causes and cures for scurvy. Thankfully, we do not follow Talmudic medicine.

Generally speaking it is prohibited for a non-Jew to heal a Jew if the wound is serious enough that we could transgress Shabbat for it (such as scurvy). The fear is that the non-Jew will surreptitiously kill him. But if the person being healed is an important man like R. Yohanan, then we are not afraid that the non-Jew will kill him.

R. Abahu was also a distinguished man, yet the Jacob the heretic tried to poison him. Had R. Ammi and R. Assi not licked his leg R. Abahu would have lost it. This proves that heretics (or non-Jews) will try to poison Jews.
The answer is that the woman who healed R. Yohanan was an expert, and thus would not risk her reputation by trying to harm an important man like R. Yohanan.

R. Abahu’s doctor tried to kill him even though he is an expert physician because he was not just a non-Jew, he was a heretic (he may have been a Christian). The enmity of this group against the Jews is sufficient that they would be willing to die in order to cause them harm, just as Samson was willing to kill himself in order to kill the Philistines.

The amoraim continue to list what types of wounds are serious enough that one may desecrate Shabbat for them. The Talmud then lists how these wounds are cured.

More medical advice, this time concerning boils that look like grapes. Ouch!