This all start in December 2017 when I saw blood in my stools, since there the blood was reduced or disappeared but I started to see white things in the stools. Believing that I have parasites I went to my doctor and I need to take some pills. Yesterday I had diarrhea (I believe is because of the pills) and I saw some black and red pieces in stools, black pieces is also not the first time in last 2 months. I also have for like 1-2 weeks lower back and sometimes hip pain, I believe this is not due to my bowel problems because I had some back problems, but I'm scared this is all related and I could have something worse.
I'm a 17 years old male