IS it okay to leave my shin abrasion alone?

I fell from a hurdle. And got a abrasion. There was white (platelets? ) thing around it and blood. I washed it with really clean water and just put a plaster over it and change the plaster every half an hour. Must I see a doctor coz it costs like 60 bucks and I m just a student. Will I get an infection??? It's quite small and doesn't hurt. It s starting to bruise though.