Harry's Scar / Snape switched the locket ,/and other theories

[Auria]

No: HPFGUIDX 134909

I have two questions which I'd like other people's comments on:

1. In HBP how come Harry's scar is no longer hurting him?  Throughout 
OoP his scar started burning or being painful when Voldermort was 
near or having strong emotions, hence the reason Harry had to learn 
Occlumency.  But he never managed to master Occlumency, so surely 
this would mean LV could still link to Harry through his scar or his 
mind?  There is no explanation in HBP why this has suddenly changed.  
Anyone have any thoughts on this?

2. When Harry retrieves the locket from Dumbledore's pocket after he 
has been killed by Snape, Harry notices the locket is smaller than 
the one he remembered seeing in the Pensieve right? Well, is it 
possible that DD and Harry DID retrieve the real horcrux locket but 
that it was switched by Snape and Malfoy from DD's body at the foot 
of the tower just before Harry caught up with them?  If so then this 
would mean Snape IS a triple agent and has taken the real horcrux to 
destroy it.
Could this be possible?  

I'm also enjoying the theory I read on some posts that DD's 'Oho!' in 
the cave means it is really Slughorn.  Afterall, we never got an 
explanation in HBP as to why Slughorn had made the vat of Polyjuice 
potion in the first place.  I guess I'm just hoping that DD's in not 
really dead. It doesn't bode well however that DD's portrait appeared 
in the headmaster's office, but again this could be another part of 
DD's plan to fake his death.  We can only hope!!! :-)

Rita