I Have Intense Stomach Ache And I Have Had Bad

I have intense stomach ache and I have had bad diarrhea over the last few days. Last night I had thought I had to go to the toilet due to my stomach ache, I went to the toilet and stringy sticky stuff had been released from my anus. When I wiped this stuff away I saw an almost a very small creature (which I think is a parasite) swimming around in the liquid. I don't know what to do and I think I may have an infection.