Most probably, it is upper respiratory tract viral infection. This has nothing to do with sex. It is a co-incidence. You had protected vaginal intercourse so there is very little chance of STI. Chances of getting STI through unprotected oral sex is very low unless you have ulcer or fresh cut mark in your mouth or in his penis. But for completely ruling out STI, I recommend you to get tested for STI if you are not sure about your partner’s STI status. Advice for you 1. Azithromycin 500 mg daily per oral for 5 days 2. Levocetirizine 5 mg daily orally for 5 days 3. Paracetamol 500 mg orally if headache occurs. Otherwise avoid it 4. Do gargle with chlorhexidine mouth wash every 8 hours 5. Always ask your partner to use condom during sex 6. Investigations a. VDRL b. HIV SCREENING c. HCV DNA screening d. HBsAg Thanks