Hello
Thanks for posting your query at DoctorSpring.com
First of all , repeated and frequent intake of the morning after pill is ineffective, will mess up your periods ( like it already has ! ) and just adds up side effects instead of providing reliable contraception.
In future, please use reliable contraception, and avoid use of the morning after pill.
The spotting is mostly due to the 3 dosages of- the morning after pill.
Just have an STD screen as you have rightly decided to do.
Also, such spotting, particularly after sex, could indicate a cervical condition -erosion, cervicitis ( infection ), a polyp, growth etc.
In addition to an STD screening, it is best to have a thorough gynecological evaluation.
This would include an internal exam - per vaginum and per speculum.
Also, a pelvic transvaginal ultrasound scan.
A Pap smear also should be done.
Stress, anxiety, hypothyroidism, erratic eating, late nights, smoking, drinking, travelling, exercise - all this too can cause spotting.
All the best
Please feel free to discuss further.
Regards.