A complete personality transplant. Help!

This is a really odd thing to be asking, I know, but have there been periods where your personality has drastically changed? Is a leopard really capable of changing its spots?

Only prob though is that it's changed for the worse.

I am quite a shy person in general, but that hasn't put me off having good times and whatever. A cliched person who opens up eventually. There are times and people around which I could be myself around, muck about, enjoy myself.

However, that was a year ago. For a year now I've become withdrawn and unable to have fun. Nothing really excites me anymore, at a time where I will be graduating, turning 21, going to the states. It should be a really exciting time. So why aren't I feeling it?

Everything I do now is internally scrutnised: no matter who it is to now and the situation I'm in. I always watch what I say to make sure it's acceptable, act stern and sensible although I never was like this. It's only until I got this pointed out by my best friend, who even I feel self conscious around now, whom I never felt that way around before. Groups that I used to be myself around have made me feel scared before meeting them now, and I get all withdrawn. I have a feeling that people are drifting away from me.

I'm all for new beginnings, but what if this is a recurring pattern that I can't break out of? I'm really scared tbh. Sorry for the melodrama but it's really affecting me. I feel like I'm not being true to myself or others. Cheers.