Your prayer is valid and the secretions are pure (tahir), and what you have seen is neither maniy nor wadiy; rather it is pure moisture, because it does not have the characteristics of those two things.

If someone does tayammum for janabah because he has a valid excuse, then he becomes impure in the sense of minor impurity, he must do wudu if water is available, and he is not required to repeat tayammum or do ghusl so long as his excuse is still applicable, because tayammum removes impurity temporarily and it takes the place of ghusl until the excuse is no longer applicable.