You did sex on Friday and notice mild spotting today.It may be due to hormonal imbalance,stress, psychological upset etc.
All other features related to PMS(Pre Menstrual Syndrome).
Several measures to be taken.As follows:
1) avoid stress by deep breathing or yoga
2) avoid taking salt,caffeine or fatty food specially in 2nd half
3) take Pyridoxine
100mg daily with SSRI (Fluoxetine
20mg single dose)
4) may take OCP or progesteron pill (Duphaston
10mg) to overcome other symptoms
Wait for next coming period.If missed or delayed,do a home pregnancy
test for urine/blood after 1 wk. Then consult with your doctor.