Hi doctor, I had an anal intercourse with a woman...

Did you get infected by your partner?
Well, unless your partner is clear of infection, there is nothing to be worried about. However, if your partner is infected, then there is a chane to get the infection.
Treatment of STI ?
Sexually transmitted infection caused either by bacteria which is easier to treat or viral which is harder to treat. So if there is bacterial infection, antibiotics will be prescribed such as ceftriaxone and doxycycline (for chlamydia and gonorrhea). However, if there is viral infection such as herps or HIV infection, antiviral medications will be prescribed. It should be noted that your partner should have to get examined.

Diagnosis?
History and physical exam to be done by the doctor. Blood tests including CBC, HIV testing as well as urine test to check the infection. 

Signs and symptoms:

• Painful or burning urination
• Genitals and oral sores
• Penile or vaginal discharge
• Pain during sex
• Fever
• Lower abdominal pain
• Rash

Advice:
It's recommended to visit the urogenital clinic for further assessment

PEP (post-exposure prophylaxis) means taking medicine to prevent HIV after a possible exposure. PEP should be used only in emergency situations and must be started within 72 hours after a recent possible exposure to HIV.