Hi,
It is possible that the 
abdominal pain and vaginal bleeding with clots could be related to the HCG trigger shot. The HCG trigger shot is typically given to trigger ovulation in women undergoing 
fertility treatments. The shot can cause some side effects, such as abdominal discomfort or pain.
However, it is also possible that the bleeding and clots could be related to 
pregnancy. It is important to speak with your healthcare provider to determine the cause of the bleeding and abdominal pain. They may recommend a pregnancy test or other diagnostic tests, such as an 
ultrasound, to help determine the cause of your symptoms.
It is also important to seek medical attention right away if you experience heavy bleeding or severe abdominal pain, as these could be signs of a potential complication, such as an ectopic pregnancy or 
miscarriage.
Take care. Hope I have answered your question. Let me know if I can assist you further.
Regards,
Dr. Priyanka, General & Family Physician