So first, you don't know that she's a "crackhead", and even if she is an addict or a prostitute, that doesn't mean she is infected with anything. I know you are anxious, but catastrophizing this isn't going to help. (Shaming people won't either, since what you did isn't any better or worse than what she does.)
So facts. Receiving unprotected oral sex does put you at risk for a few things - gonorrhea, syphilis and hsv1. None of them are likely. You can also get NGU, which is an infection in the urethra, from normal mouth bacteria.
Gonorrhea is probably the most likely. It's more common than syphilis, and she doesn't have to have visible symptoms to transmit it.
Syphilis isn't all that common in developed countries, though it's definitely out there. If she didn't have visible sores on her mouth, I wouldn't worry too much about this.
Hsv1 can be transmitted from the mouth to the genitals, resulting in genital hsv1. If you have herpes type 1 already (think cold sores or fever blisters) then you have antibodies that protect you from getting this again in a different location.
Honestly, I wouldn't overly worry much about this. The exposure wasn't that long, the only common thing I mentioned is hsv1, and you may already have that. Your current girlfriend may already have it. (Up to 80% of the population has it - your chances go up the older you are).
Since drinking so much causes problems for you, maybe take a look at that, and take a look at your friends who clearly don't have your best interests in mind. STDs shouldn't be at the top of your list of concerns - the risk doesn't warrant it.
If you want to test for gonorrhea and NGU, you can after 3-5 days. Syphilis is 90 days, though most will test positive by 6 weeks, and herpes can take up to 4 months, though most will test positive by 6 weeks. You can ask your doctor for a type specific IgG blood test now to find out if you already have hsv1. If it's positive now, it's a pre-exisiting infection.
Again, though, I wouldn't overly worry.