The root cause can be caused by over fermentation of he food and slow food transit. Inadequate emptying of he bowel when you go to the toilet and even menstrual problems. Stools and how they are formed gives a better clue to whether you have constipation, diarrhoea or alternating bowel movement.
Treatment is complicated and consists of changing lifestyle habits, spreading food throughout the day, changing the foods you eat, exercise, etc.
Probiotics can help but your colon sets the allowable bacteria in the colon when we are babies and the balance can't be permanently changed. Consequently, if probiotice do help you have to keep taking them. Prebiotics often feed the bad bacteria as well as the good and may make things worse.