What Causes Lower Abdominal Pains And Constipation?

Around 2 and a half weeks ago I was playing soccer, in goal. I dived to save a shot, landed on my arse and injured it. Over the next week and a half I ontinued playing and further injured it about 3 times.
Last Thursday, a week ago, I did it again. It hurt most that time. Next day I could barely walk and since last Friday i've only been able to go the toilet (solids) once. I've also had aching pains round my kidneys and pains throughout my back and abdomen.
What could I have done?