Praise be to Allah.
Firstly: if your regular period has ended, what you saw was yellowish or brownish , so you should not count this as anything. Rather you should fast and pray, because of the hadith of Umm `Atiyyah (may Allah be pleased with her) who said: “We used not to count the yellowish and brownish discharge that appeared after becoming pure as anything.” (Narrated by al-Bukhari, 1/426).
This is when the period has finished. But if the yellowish or brownish discharge appears during the time of the period, then it is part of the period. For example, if your period lasts seven days, and on the fifth day the bleeding stops and you see a yellowish or brownish discharge , this is part of your period and you should not pray or fast.
If what you describe happens every month, then you should do ghusl when it stops and you see that you are pure. If the drops are very few and it does not happen every month, but it happens sometimes and it is not pure blood but is yellowish or brownish, then this does not count as anything and you do not have to repeat the ghusl. If it is there it is the same as if it is not there; do ghusl when you see that you are pure.
And Allah knows best.