I’ve been sick for over 4 years. I have stomach pain, cramps, diarrhea, mild constipation, mild headache, mild nausea, fatigued?

I am 53 year male, I’ve been sick for over 4 years. I have stomach pain, cramps, diarrhea, mild constipation, mild headache, mild nausea, fatigued. I’ve seen several doctors and had 2 endoscopy 2 colonoscopies had my organs check and my brain, and everything seems normal. I now believe i might have a parasite in my intestines