Suggest Medication For Constipation & Bad Odour From Rectum

Hi, about 2 years ago i was having really bad constipation and a really bad smell coming from my rectum, so i went to the doctors and he told me to change my diet, so i did and i lost weight and everything was fine for a couple of months, then it came back with diarrhea included. I would also get really itchy rectum at night. About 6 months ago everything seemed to have spiralled out of control. I got a random fever that lasted maybe an hour or so, then i got ear infection and flu. A couple of weeks later at night i woke up gasping for air, jumped up and couldnt breathe properly for a couple of hours and felt disoreantated, i managed to get to sleep and everything was fine during the day, it happened a couple more times after that but always around 1am in the morning. A couple of weeks after that i fell ill and all the symptoms have flared up and i feel as if im in a bubble, memory is bad, concentration is bad. I have tried over 5 different doctors and they dont know what it is. I convinced one doctor it could be worms, he has given me Menbandazole or something and i have seen white worms and also red ones, my stool is dark black and has mucuos all the time.