Well I had a nice paragraph written for a reply, I hit tab accidentally and my browser was kind enough to "back" and erase it all. >/ Abridged version: I was about the same way, then I went through a situation that turned me introspective and let me see things like this and how to overcome them. A possible solution, one that works for most is: find something that you think you're really good at. A talent you have that just seems to come naturally, or just feels right. For me it was making music, on any instrument. Once you identify it, hone and strengthen it. Then, the final step is to take pride in it, and take pride in YOURSELF for it.
If you want to know why I think this will work for you, here's the reason, it is.. your reasons.
"Generally, I tend to lie about things to cover up embarrassment in my life, to make myself more interesting, to make excuses, or for undeserved sympathy." The general that can be derived from these specifics is that you simply CARE TOO MUCH about what people think of you. I thought the exact same way, and handled things almost exactly the same as you, and I found this out. But people would tell me that the reason I was so unliked was that I cared TOO MUCH about others' opinions, but no one would tell me how to FIX it. "Sure, ok, I'll just randomly stop caring with absolutely no idea how. ok.
So I am telling you what worked for me, who knows, it might work for you. Just don't let what other people think of you get you down. You are who you are, and you have a unique gift whether you know what it is yet or not, and therefore you don't need to care what they think. If they don't like you, it's their loss.
In closing, I hope this helps, despite my post-long day at work exhaustion and my ******-offery at the fact that my browser erased my first draft. lol. But it never hurts to see a psychologist, they can identify underlying factors or other things better than I could simply through text. I'm good, but not that good.
Well anyway, good luck!