like I said, the more you relax and stop thinking, stop doing this, dont do that, then the better you will feel and the easier it will become, it sounds to me that one ore two bad habbits have sneaked in and now your confidence is down, the less you think about batting the better, if you just play each ball on its merit and dont try to do too much, then it should be okay. I think the main points to focus on, are cocking your top wrist, lighten the grip on the bottom hand, and stay as still at the crease as possible. Another problem could be that your back hip is pushing through bringing your back shoulder through, this in turn would push your bottom hand through, but again without video its impossible to say weather or not thats the problem. If you think that is the problem then the easy fix for this is that you need to keep your back foot parallel to the stumps and crease, and dont turn your foot and rock onto the front of your toes. ALOT to think about I know, but like I said, it all sounds like small issues that have a realatively easy fix that amount to a bigger issue.