Unprotected sex can lead to any Sexually transmitted disease
.Manifestation of the symptoms depends upon the incubation period
of the organism.
As per your query,it is evident that you are thinking of HIV.
If you are very much doubtful,get a blood test
and/or diarrhoea are not specific for HIV.In some,they may be present and in some they are absent.
Hope the test will come negative.
Wish you good health