Irritable Bowel Syndrome Treatment

My 2 1/2 yrs old baby is very much constipated, we have tried several attempts to help him such as shifting of milk, use of laxatives , intake of yougurt, yakult, cereals , etc. but it doesn’t work that much. Usually it would take 3-4 days before he can finally release his poo. It’s very alarming. Just want to know if someone out there have use this probiotics OMX to their toddler with the same problem as mine. I’m planning to use this for my son.