Could I be pregnant after missing period?

In the case of the mother having Rh-negative blood and the baby Rh-positive blood, there are measures to ensure a safer pregnancy. One choice is the injection of a substance known as Rh immunoglobulin within 72 hours after some procedures, such as an abortion. In this way, your body will be prevented from producing dangerous antibodies. Such a therapy is essential in the possible protection of future pregnancies from any complications.

Yeast infection might be why your clitoris itches. When the pH balance of your vagina changes—usually after having unprotected sex—this can occur. To relieve the itching, try using over-the-counter antifungal creams or ask for a prescription from a doctor. To avoid getting infections, always use condoms during sex.

if you have at risk sex close to your period, delay or wait.
There is an option for emergency contraception pills, however they are not 100%.
Use condoms to avoid pregnancy and getting sexually transmitted infections.
Consult a physician for further advice and routine follow-up.s

On average, the menstrual cycle lasts from 3 to 7 days. There are pregnancy possibilities even if having sex at any time, but the chances are greater during ovulation, which usually occurs on the 14th day of a normal cycle. If your period started 4 days ago and you have a 28-day cycle, ovulation could be in place now. 

Breast pain could be due to many reasons including hormonal changes, breast cysts or fibroadenomas. I propose that you consult your gynaecologist for a clinical breast examination and possibly a breast ultrasound to find the underlying reason of the pain.