I can assure you that it is not an STD I have had same issue and have been tested for STD everything came back negative.
Most likely a Yeast Infection. Take some Monistat 7 And if symptoms persist see a GYN.
STD don't show up immediately, so unless you've had unprotected sex previously it's probably not an STD. Still it's not a bad idea to get tested, just to make sure. If you notice any bad smells, odd discharge, or itching/burning -those are the general symptoms of an infection (STD, yeast and bacterial included). Note you don't need all these symptoms to have something and you can carry STD's without any symptoms at all. Burning and itching can also be caused from too dry of sex. Watch for discharge and if the symptoms go away then it's likely from too little lubricants.