The other possibility is of threatened
miscarriage. To prevent threatened
miscarriage, I would suggest you to avoid
intercourse especially during the first trimester.
I hope it helps. It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.