All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ʻalayhi wa sallam, is His slave and Messenger.
We ask Allah to bless you with perfect recovery and wellbeing. You should know that the remedy for obsessive doubts is to ignore them and not pay any attention to them at all. Letting yourself get carried away with them leads to grave evils. If you doubt whether you have discharged any impurity or not, then the basic principle is that no impurity was discharged. If you know with certainty that you have discharged an impurity, you may follow the opinion of the Maaliki scholars, who held that it is not obligatory to take precautions (to prevent the discharge from spreading onto your body or clothes) in such a situation.
As for the toilet paper in reference, the basic principle is that it did not fall on the floor, and, in principle, this piece of paper that you found is pure. So always follow this principle, act upon it, and do not do otherwise so that you do not cause yourself extreme inconvenience.
Allah knows best.