Answered by Shaykh Yusuf Weltch
Question Summary
How do I know if bodily fluid is sweat from discharge from the penis or anus?
Question Answer
In the Name of Allah, the Most Merciful and Compassionate
The basis is that everything is pure until proven impure. [Ibn Nujaym, al-Asbah wa al-Nazair]
That said, purification is based on reasonable surety or certainty. Doubts, misgivings, and conjectures are always to be ignored. You are not accountable to act on anything less than reasonable surety.
Consider the discharge as sweat. Sweat is pure. Remember, you are not required to smell anything.
Please see the following links as well :
https://seekersguidance.org/answers/hanafi-fiqh/transfer-filth-occur/
https://seekersguidance.org/answers/hanafi-fiqh/ocd-causing-hardship-impurities/
Hope this helps
Allah knows best
[Shaykh] Yusuf Weltch
Checked and Approved by Shaykh Faraz Rabbani