I did not cut my nails before Yom Tov. I have an appointment by the foot doctor, on Hoshana Rabbah. May I trim my toenails before the appointment?
If there is a need for this, it is permitted to cut toenails.
According to the majority of early authorities, there is no prohibition against cutting toenails on Chol Ha-Moed (Rif, Rambam, Rosh, Semag, and Shulchan Aruch 534:1).
However, some are stringent on cutting nails on Chol Ha-Moed, so that a person will ensure that he will cut his nails before.
This stringency is ruled by the Rema (532:1), though it will not apply to somebody who cut his nails before Yom Tov (Magen Avraham and Mishnah Berurah; Aruch Ha-Shulchan 2; see also Nachalas Shiva 2:57 concerning somebody who cuts his nails regularly before Shabbos, and the Aruch Ha-Shulchan concerning somebody who didn’t have time to cut his nails before Yom Tov).
Based on the rationale of the halachah, it appears that there is no constraint on cutting toenails on Chol Ha-Moed, because in the case of toenails there is no reason to encourage cutting nails before Yom Tov. [The Gemara states explicitly that toenails have the same basic halachah as fingernails.]
Although the general custom is to treat toenails as fingernails, where there is a need it is thus permitted to cut toenails.