I went to toilet tonight and after i urinated noticed a very tiny dot of blood, half the size of a grain of rice, also a burning feeling. what is this?

Probable UTI: This is most consistent with a urinary tract infection (UTI, bladder infection). An STD like gonorrhea or chlamydia may be possible if you are sexually active, but probably not. In any case, you need to see a doctor or clinic ASAP for exam, testing, and probably an antibiotic prescription. (If sexually active and need confidentiality from parents, go to your nearest NHS GUM clinic.) Good luck!