I recently stopped using the injection and got my period 5months later after my period stopped, i had unprotected sex and want to know what is the chances of me falling pregnant after that?

Risky: Any incidence of unprotected sex (e.g. absence of pregnancy prevention measures), particularly in a scenario where there is a suggestion of ovulation--e.g. periods--puts one at risk for a pregnancy. I would do a urine pregnancy test and repeat one a week later. In the meantime, consideration can be given to emergency contraception (Plan B).