What Causes Blood In Urine After Landing On Knees Post Jumping?

My 2 year old son fell about 1.5 metres from a tree branch today and landed on his hands and knees. He immediately got up complaining about the top of his right foot being sore and this seems to have gotten worse throughout the day. We will take him to our local doc in the morning but in the meantime - just now he went to the loo and said 'his wee had blood in it'. We asked if it hurt and he said "no it didn't sting - it just hurt"! Pretty good communication thank god - but could this blood be a result of his fall?