bowel movements

can someone please explain to me what these are thats coming out in my stool. I have them every few months. I have a very active bowel ( i go as soon as im done eating). Most of the time the stool is diarrhea like or very hard like constipation. I have also notice odd things in the stool like long strands of mucusy looking things. They look very much like roundworms or whats left of a dead worm. Stool usually smells beyond horrid and is often greasy looking. I do have some abdominal pain sometimes before i have to go to the bathroom. I have had a stool sample tested about 2 years ago and it came up negative for parasite but i think the technician must have missed something. These below are ones that just came out that seams like some type of casing. They are very think and translucent.





These scaly skins though totally have me
drawing a blank...could it be intestinal lining, potato skins or something else










this is what it looks like up close with the snake like skin pattern