switching breasts? My LO will not re-latch!

pregmama

My LO's doc recommended switching breasts after 10-15 minutes... then going to the other and letting him nurse until he is done. Then at the next feeding start with the alternate side (the one you didn't finish with). Is this a correct method? Something to do with foremilk / hindmilk? I guess it is suppossed to help with nursing a little less frequently? Also, if I am suppossed to be doing this I have an issue: My little guy will not re-latch to the other side when I try to switch him over.