I used to deal with severe constipation where I would get so backed up there was a fear by my doctors that it cause some major problems. Nothing worked for me. I recall having to take meds and try enimas but long term it did not help. Now I seem to be having the opposite problem.
A few things I tried during the long time I had constipation. First it depends on the your digestion but often more fiber can make things worse especially if you dont have enough fluids. Some foods cause more of an issue such as dairy. Having enough healthy fats to lubricate is important. Often ground flaxseed is helpful. Also prunes or prune juice. If you cant tolerate that try baby prune food. I know it sounds weird but a dietician once said it is easier for people. Some activity if you can do it. I also agree about magnesium.
Also to get things started if your doctor says it is ok a stool softner. I remember years back when I was in the hospital they gave me a tennis ball to toll on my lower stomach that was supposed to help get things moving. I dont know if this is true because at that time nothing helped me like that but everyone is different. Also coffee helps many.