TLDR: Back in college, I used to be socially confident in myself and outgoing. Went through a rough, anti-social phase after graduation because of my job, and now I've become shy, introverted, and totally unconfident in myself (socially at least). Looking for advice.

I went to a mid-size college, was involved in a fraternity and sports, and tried to get to know everyone I could but still didn't come close to knowing "everyone" (school of 10,000 undergrads). I liked going out and meeting people, and was decently successful with girls.

After college, I started working for a male-dominated business consulting firm in a large city where a lot of my friends ended up as well. The job was pretty intense, and I was working 80ish hours a week and constantly traveling, so for a while (basically the first half of 2014), I was only able to actually meet up with friends and go out a few times (probably less than 5 times total). Every time we went out, I was so burnt out that I didn't really want to be social; I just wanted to get as hammered as possible, and on the way, I didn't really want to interact with anyone new, even as my friends were introducing me to people they had met. Specifically, I had a hard time talking to girls, and the few times that I did make an effort, I really crashed and burned, which was a huge change from college (side note to myself: social conversation is a skill that you DO need to practice).

This past summer, I finally decided I'd had enough and quit for another, less stressful position. I've got a lot more free time now and go out with my college friends quite a bit. The issue is that while I'm not getting sloppy drunk that often anymore, I'm still somewhat anti-social, and I have an especially hard time opening sets, which was never the case before. People can sense my apprehension, and since I'm getting shot down a whole lot more, it's also getting to my head now, whereas in college I would have just shrugged it off and went right up to the next cute girl. It's gotten to the point where I'm nervous and unconfident even with girls that are definitely interested in me (for example, girls that my female friends know and have tipped me off about). The funny thing is that my job requires me to be social (at least, in a professional context), and every day I'm meeting/talking with new people, which I have no problem with, as long as it's in a business environment; I'm just having a lot of anxiety in situations that are purely social.

Has anyone gone through anything similar? I feel like I'm stuck in a rut and not sure how to get out. Thanks for reading.