Hi there, I have understood your concern. I will suggest you the best possible treatment options.
First of all do not panic.
As you had sex act on 3rd of September, that date is well beyond fertile period of cycle of August.
Still to clear the doubt, I will suggest you to get morning's first sample of urine tested for
pregnancy. In case of doubt blood
beta HCG test and USG will be of help.
If the test result is negative, then your symptoms can be due to PMS -
premenstrual syndrome. In that case, I will suggest you to opt for a healthy diet and regular exercise regimen. Start on long acting form of Vitamin B 6,
vitamin E and evening primrose oil supplements on daily basis at least for next 3 months.
With negative result you need not worry about the pregnancy. You can simply wait for the onset of periods or induce the periods with a course of
progesterone tablets. Your treating doctor can guide you further about the doses and withdrawal bleeding after the tablets.
If you are pregnant, you can continue the pregnancy, if you want. Else you can opt for termination of the pregnancy with medicines safely till 9 weeks of pregnancy under medical supervision.
I hope this answer helps helps you.
Thanks.
Dr. Purushottam Neurgaonkar