My advice is pretty much what the others have said - fruit/veg, fibre supplements like psyllium, and don't be afraid of using stool softeners like lactulose - it can take weeks for things to heal and often people make things worse by trying to stop too early. But if it doesn't start improving then definitely see the GP. You can have both haemorrhoids and fissures at the same time. There are medicated creams you can get to relax the muscle spasm and help the fissure heal. But if you're still getting lots of pain or bleeding even while using all those things ask for a referral to a colorectal surgeon.