Reference: Fataawa Ramadhaan – Volume 2, Page 462, Fatwa No.396
Fataawa al-Lajnah ad-Daa.imah lil-Buhooth al-`Ilmiyyah wal-Iftaa. – Fatwa No.4449
Question: A man travelled whilst he was fasting in the month of Ramadhaan, and after the Zhuhr prayer he was taken by surprise when blood began to flow from his nose and mouth. In spite of that, he did not break his fast, instead he continued to complete the fast for that day. So what is the ruling regarding that, and should he make up [the fast for] that day, bearing in mind that a number of years have now passed and he has not made up [the fast for] that day until now?
Response: There is no affect [on your fast] due to the sudden flow of blood from your mouth and nose, so long as you [continued to] abstain from that which breaks the fast until sunset. [And this is the case] whether there was a little [blood] or a lot, so your fast is valid and you are not required to make it up.
And with Allaah lies all the success, and may Allaah send prayers and salutations upon our Prophet Muhammad (sal-Allaahu `alayhi wa sallam) and his family and his companions.