Warning - some might find this post a bit too graphic!
Although I try hard to keep up my fibre intake and drink lots, I have a serious constipation problem. Imo this is not necessarily due to my very low carb diet, though I expect that doesn't help. To keep myself out of A&E (seriously - impacted stool can require emergency treatment and I have come very near needing that a few times) - I have regular recourse to glycerol suppositories. They are prescribed for me by my GP, but they can be bought over the counter. Imo they are much preferable to laxatives, as they are obviously not ingested, and in the nature of things come out of the body fast. They are made from peanuts oil and are like little jelly torpedoes.
Good luck!
PS these are much cheaper at Superdrug than at Boots:
https://www.superdrug.com/Health/St...lief-Suppositories-X-12/p/633164#pdp__details