So receiving unprotected oral sex puts you at risk for syphilis, genital herpes type 1, gonorrhea and NGU.
Syphilis isn't that common, and your partner would have had to have a sore in her mouth to transmit it. You wouldn't see symptoms of this for 10-90 days, but the average is 21 days, and you'd get a sore called a chancre. This doesn't cause burning, pain, discharge, etc. You can test for this at 6 weeks. If you get symptoms, but test negative at 6 weeks, test again at 90 days.
If you don't already have herpes type 1 (think oral sores, like cold sores but not canker sores), then you could get genital herpes type 1 from receiving oral sex. This can happen even if the person performing oral doesn't have a sore, but it's more likely if they do. The time from infection to symptoms is usually 2-12 days, but the average is 4 days. You can test for this now, and then again at 4 months to make sure you don't have it. If you test positive now, it's a pre-existing infection that you had before this encounter. About half the adult population has this, and 90% don’t know it.
You'd see symptoms of gonorrhea at about 2-5 days, and this would usually be a discharge, burning, etc. Some people don't get symptoms. You can test for this as early as 3 days, but 5 days is better. You can have a urine test or a swab test.
NGU is an infection in the urethra that is caused by anything other than gonorrhea (nongonococcal urethritis urethritis, sometimes called NSU, for non-specific). This can be caused by normal mouth bacteria entering the urethra, and the symptoms and testing times are the same as gonorrhea.
There is definitely a risk here, but oral sex is lower risk than intercourse.
I wouldn't panic, but testing is never a bad idea, especially if you've had other encounters.