Praise be to Allah
We ask Allah to heal you and grant you relief from this waswas, because waswas is a kind of sickness by means of which the shaytan causes anxiety and depression to the believer. We advise you to be patient and to turn to Allah and ask Him for healing and recovery, for He is All-Hearing, Ever Close and Ever Responsive, may He be glorified and exalted.
You should note that the best remedy for waswas is to ignore it and not pay any attention to it.
Your fasting is valid, and you do not have to repeat any of the fasts, even if you intended to repeat them, because it is, as you know, waswas, and there is no reality in it. Please see the answer to question no. 39684.
The emission of a yellowish or brownish discharge after the white discharge is not hayd (menses), because Umm ‘Atiyyah (may Allah be pleased with her) said: “We used not to count the brownish or yellowish discharge after the end of menses as anything.” Narrated by al-Bukhari and Muslim .
And Allaah knows best.