I had unprotected oral sex (I'm a man and was giving oral sex to a woman) on Tuesday and on Friday i feel a little bump and my tongue is sore.  Feels like a cold sore coming on, which I get from time to time on my tongue.   I actually felt the sore developing on Thursday.  Question is, is this an STD symptom or is it too quick given the incubation period for STDs with this type of system.  If it is an STD symptom, is this too early to get tested or since symptoms are occurring a blood test would be accurate?  What type of STDs could this be a symptom of?

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I am prone to get canker sores on my tongue and mouth especially when tired or have lack of sleep, which i did in this case.  Even if it was an STI, it would be too early for the symptoms to show, correct?  Also, if by some small chance if this is an STI and symptoms came early, it means it would be in my blood stream and show up in my blood test I took this morning correct?  Just in case i am that 1 percent. 

Once again, lesions on the locations you describe are typically canker sores which are NOT HSV/cold sores.  Precisely what causes them is unknown but there are no data that they represent a hazard to sex partners.  Blood tests are not helpful for diagnosing canker sores and we recommend against blood tests to herpes in cases such as yours.  HSV blood tests do not reliably become positive until 8-12 weeks after acquisition of infection and in your case, were you to have a HSV blood test at this time, it would represent prior infection, not recently acquired infection and you would not know when you had acquired the infection, nor from whom.  I recommend AGAINST blood tests in your virtually no risk situation for recent infection.  EWH
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I also failed to mention that she performed unprotected oral sex on me.  no intercourse however.  

Not a minor omission.  Receipt of oral sex is associated with a small risk for infection with Gonorrhea, Chlamydia, and non-gonococcal urethritis.  All these infections are rare however since most persons, even most commercial sex workers are not infected and most exposures to infected partners do not lead to infection.  Further, these syndromes are typically symptomatic with burning on urination or penile discharge within a week of exposure.  It is unlikely that you were infected..  If you want to rule out these infections a urine test for gonorrhea and Chlamydia at this time would reliable prove whether or not you were infected.---