This indeed was a high risk exposure, especially if there was actual anal pentration. That seems a little unclear, but the 'slimy liquid' suggests it. Still, the chance of catching HIV, if your anonymous partner had HIV, approximates 1 in 500. On average, being uncircumcized doubles the risk--so your 'so much more dangerous' statement translates to well under a 1% chance you were infected. And you don't know that the guy is HIV positive. So on balance, the odds are very strongly in your favor.
Your symptoms don't suggest HIV. Their presence is irrelevant to assessing your risk. Because of the exposure, not the symptoms, you need HIV testing. I suggest an initial test about 4 weeks after the event; by that time, more than 90% of infected people have positive tests, so a negative result will be highly reassuring. You should then have a second test 6-8 weeks after the event. Most authorities still say 3 months, but with modern testing, it really isn't necessary. But you will get advice to that effect, which probably will be anxiety-producing--- so you may as well wait until then for your second test.
In the meantime, try to relax. The odds really are strongly in your favor. But let this be a teaching experience. Safe sex doesn't always go as planned; and when it doesn't, it generally is less safe than originally expected. NEVER have sex with another guy, oral or anal in either direction, without asking and sharing HIV status; and never have anal sex without a condom. If you follow these guidelines, you'll probably never get HIV. If you don't, the odds are strong you will get it someday.
Good luck-- HHH, MD
In any case, your chances of contracting HIV from this are really quite low; Dr. Handsfield pointed out it's less than a 1% chance. I'd say those are pretty darn good odds. I really wouldn't worry about your symptoms while you're waiting to get tested--they mean nothing, and all you'll end up doing is making yourself crazy :-)