So long as there was no bleeding immediately before or after this discharge, and it was not accompanied by the usual pains (cramps) of menses, it is not menses. That is because of the report narrated by al-Bukhaari (may Allah have mercy on him) in as-Saheeh (326), under the chapter heading: Yellowish and brownish discharge at times other than the time of menses, from Umm ‘Atiyyah, who said: We did not regard the brownish and yellowish discharge as being of any significance.
It was also narrated by Abu Dawood (307) as follows: We did not regard the brownish and yellowish discharge after menses ended as being of any significance. It was classed as saheeh by al-Albaani in Irwa’ al-Ghaleel (1/219).
Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said:
Regarding the yellowish and brownish discharge, there are three views among the fuqaha’ concerning that. According to the view of Ahmad and others, as to whether it is menses in all cases or is not menses in all cases, the third of view – which is the correct view – is that if it is part of the menses and occurs with the black (dark) and red blood, then it is menses, otherwise it is not.… Umm ‘Atiyyah said: We did not regard the brownish and yellowish discharge after menses ended as being of any significance." (Majmoo‘ al-Fataawa 26/220).
This has been discussed previously in the answer to question no. 179069 .
This discharge invalidates wudoo’, but the sa‘i of one who experiences that is still valid, because it is not stipulated that one should be in a state of purity when doing sa‘i. In the case of tawaf, however, most of the scholars are of the view that it is stipulated that one should be in a state of purity.
Other scholars – such as Shaykh al-Islam Ibn Taymiyah, and it is also the view favoured by Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) – are of the view that it is recommended (mustahabb) to be in a state of purity for tawaf, but it is not stipulated.
This second view is the one that is more likely to be correct. That has been discussed previously in the answer to question no. 34695 .
And Allah knows best.