Is it obligatory to make up the Dhuhr prayer if I performed a precautionary ghusl after a wet dream and feeling wet, given that I was not certain about the emission of semen?

The wetness you observed can be categorized into several scenarios:

1. If you are certain it is maniyy (seminal fluid): You must perform ghusl (ritual bath) from janabah (state of ritual impurity requiring ghusl), and repeat the Dhuhr prayer that you performed after seeing the wetness and before performing ghusl. This is the preponderant opinion. 2. If you are certain it is madhiy (prostatic fluid): The Dhuhr prayer is valid if you had washed the part of your body affected by madhiy, performed wudu' (ablution), and prayed with a clean garment. 3. If you are unsure of the nature of the wetness (whether maniyy or madhiy): You have a choice. If you consider it maniyy, then perform ghusl and repeat Dhuhr. If you consider it madhiy, then your prayer is valid if you had washed the impurity of the madhiy from your body and clothes, performed wudu', and prayed with a clean garment.