[A human Being]

So I've been meditating pretty intensively for over a couple of years now, meditating for anything between two and four hours a day (though I've eased off a little of late - it's more like an hour to ninety minutes at the moment), and it's really helped to shift things in terms of dissolving energetic blockages and releasing various emotions.

A development I've noticed in the last few days is that I've started to experience a cracking, grinding sound/sensation at the base of my skull, in exactly the way your bones might crack when they're being manipulated by an osteopath. It doesn't happen during every meditation and it isn't painful, but it's rather unnerving when it does happen and it makes me worry that I'm going to incur an injury. Has anyone else experienced anything like this, or does anyone know what it signifies? I'm also experiencing a lot of energy in my head and heart, could it be related to that? My heart in particular has always been a big issue, it's been very badly damaged and appears to have suffered a lot of trauma - I get the sense that the cracking might be related to that in some way, though I could be wrong.