Regarding Dog and Rabies. Or reaction?

Dear sir mem kindly read my whole problem in details. Sir i was going through a village road,as it was a raining day so their was water in the road,a truck was coming from front n it crossed over the water due to that some parts of that road water sprayed on my legs,their was a little cut on my leg of 2-3days earlier,but it was covered by black skin and i saw a dog was drinking other part of water on the road,so i got worries if the dog has also drunk the same water that sprayed on me,So my question is That (i).because the water touched my legs and their was old little wound of 2-3days earlier so Can i get rabies?? (ii)Should i have to take vaccine?? If yes then how many vaccines?? (iii)Earlier i have taken 12vaccine of Rabies from 2008-2012,so if i again take vaccine will there be any side effect or reaction????   TODAY I VISITED TO A LOCAL MD DOCTOR HE SAID NO NEED TO TAKE VACCINE IT WILL EFFECT YOUR IMMUNITY SO FORGET ABOUT IT N RELAX. SIR/MEM PLEASE SUGGEST ME WHAT SHOULD I DO