Is the fluid that exits after urination and continues for a long period, accompanied by repeated flatulence during prayer, considered سلس (incontinence) that necessitates the rulings of incontinence, especially with its recurrence and the difficulty of determining when it stops?

If the liquid that exits after defecation occurs frequently and continues for a long period, such that it does not cease before the prayer time expires, and it is difficult to control, then your ruling is that of one who suffers from سلس (incontinence). You should wash the affected area thoroughly, tie a cloth tightly over it, and perform ablution for each prayer after its time has begun. The exit of the liquid thereafter will not harm you, even if it occurs during the prayer. When the time for the next prayer begins, you should repeat the cleansing (istinja) and ablution, and wash whatever has stained your clothes.