Throat has been hurting for a month. left lymph node swelled up then went away. ultrasound and bloodtests didn't reveal throid or lymph issues. help?

Time,: Give yourself some time but if symptoms do not go away go back see the doctor one more time or see an ENT specialist.

Need work up : This could be anything from a cold to reflux (especially if you are overweight) to environmental/smoke irritation. While malignancy is not impossible, it would be very unlikely at 23yo, and malignant lymph nodes don't get better spontaneously. See a general ENT who should examine and possibly scope you to see how your throat looks. If you smoke- stop.