I have experienced the exact same thing you are going through. You can read all the details in the first post I made on here, but basically it said that growing up I was very sociable/outgoing and not afraid to talk to ANYBODY. I made friends easily, I remember at one point having so many friends that I started shunning the less cool friends. Around 6th grade that all changed. I decided I wanted a gf and I was foolishly under the impression that I had to fit a "cool guy" stereotype in order to do so. So I went all out trying to be somebody I'm not and failing miserably, I lost all my confidence and self esteem and not until recently have I gained most of it back.
Sorry for the story but it is relevant.
So first off you need to identify the cause of your social downfall. A law of physics is "things will remain the same until there is a reason for it to change" or something like that (I suck at science). Meaning that nothing just changes out of the blue, there has to be a fundamental reason for your loss of social skill. Identify that and then your on your way.
Next you said you "don't even believe what your saying". NEVER do that. You are abandoning who you are in doing so. Conversation comes from emotion-how you feel. What ever you are feeling is what you will be saying. If you are happy and feeling great, everything you say will reflect that you're feeling happy and great. Likewise if you are feeling down and "blah" (like I used to and sometimes still do) then your conversation will reflect that your feeling down and blah. If you don't respect yourself enough to say what you are really feeling, then of course you are telegraphing insecurities, which is a huge turn off to people. They will see you as "not genuine." They will see that your attitude does not reflect your vibe or your body language and then they subconsciously know "something's not right here" and they will think you are weird. (been there, done that.)
"The way people treat me has changed a lot because of this, and its starting to deeply affect my self esteem."
This is bad news. It is true that people treating you badly will have an effect on your self esteem, but there is a way around that. You are basing your mood or confidence around what people say, this is called "seeking validation" (which is where neediness comes from BTW) which is not a true form of confidence anyway. Instead, shift your focus to "internal" meaning be confident because you know who you are and you love yourself, and it doesn't matter what anybody says or thinks. This is the only true confidence.
Yes, people giving you compliments and telling your great will make you FEEL more confident, but the second you don't receive those compliments anymore, you will go right back to feeling down and blue. If you are confident with yourself, you won't be dependant on compliments to make you feel good.
So here is your homework:
Over time I have come across some very good articles and material that I believe has added so much to my confidence and helping me to better love myself, and I would like to share this material with you.
Daygame . com is a very good source of detailed information for the very things I have talked about. They have very good videos/articles/podcasts that helped me so much.
If you don't watch/read/listen to anything else on daygame . com, listen to
This podcast: (talks about external vs internal validation)
http://www.daygame.com/podcast/the-dayg ... aware-man/
And this one: (more good inner game stuff)
http://www.daygame.com/podcast/episode- ... e-beliefs/
Watch this video:
http://www.daygame.com/videos/how-to-lo ... lf-esteem/
These are the main ones but if you just surf around you will find all kinds of good stuff to help you.
You can also go to PUATraining . com/puablog for tons more articles.
I hope this helps, feel free to PM me if you have any questions. Good luck man!