Reciting Soorat al-Ikhlaas 10,000 times for a sick person
Undoubtedly in the Qur’aan there is healing for mankind; and it was narrated that in certain verses and soorahs there is healing and protection for man, and that they can ward off bad things, by Allaah’s leave, such as al-Faatihah, al-Mi’wadhatayn, Aayat al-Kursiy and Soorat al-Ikhlaas. Whoever recites some aayahs or soorahs, and repeats them three or seven times, as needed, without persisting in a specific number that was not referred to in sharee’ah, then there is no reason why he should not do that, so long as he believes that healing is in the Hand of Allaah Who has created in the Qur’aan healing for mankind.
To that may be added ruqyah using du’aa’s narrated from the Prophet (peace and blessings of Allaah be upon him), such as the words, “Adhhib al-ba’s Rabb an-naas, wa’shfi anta al-Shaafi, laa shifaa’a illa shifaa’uka shifaa’ laa yughaadir saqaman (Take away the pain, O Lord of mankind, and grant healing, for You are the Healer, and there is no healing but Your healing that leaves no trace of sickness).” (Narrated by al-Bukhaari, 5243; Muslim, 4061)
And one may do as the great Sahaabi advised, when someone who was suffering pain complained to him. He said: “Put your hand on the part of your body that is hurting and say, “Bismillaah” three times, then say seven times, ‘A’oodhu Billaahi wa qudratihi min sharri ma ajidu wa uhaadhir (I seek refuge with Allaah and His Power from the evil of what I am suffering from and what I am worried about).” If one does that, and recites other du’aa’s that have been narrated from the Prophet (peace and blessings of Allaah be upon him) in saheeh reports, that will be very good.
If trust in Allaah is combined with thinking of the meanings of the verses and du’aa’s that are being recited, and both the one who is doing ruqya and the one for whom it is done are righteous people, that will be very beneficial, if Allaah wills.
Based on the above, gathering in the manner mentioned in the question and reciting “Qul huwa Allaahu ahad” a certain number of times (10,000 times) is not something which is prescribed in Islam, so you should be content with doing that which is narrated in the Sunnah.
We ask Allaah to heal your sick loved one quickly, and to grant him good health. Ameen.