Ovulation or implantation pain?

Sarah • We just had our rainbow baby 2/3/19 after 5.5 years of ttc and 3 miscarriages.
Hi everyone! This month our specialist changed up our treatment a bit. We're doing a hybrid 100mg clomid CD3-7, FSH Shots CD7-10, HCG shot CD11 and progesterone CD15-until we get a BFP or AF shows. 
But on CD13 I started having super uncomfortable cramping while at work. It lasted all day and into the night. I took 600mg Advil and 2 extra strength Tylenol and it was bareable but still very uncomfortable.
Do you think it could or would be implantation or just ovulation?
 Soonest I can test would be Thursday morning (HCG should be out of my system by then). I do have a doc appointment already scheduled for bloodwork and ultrasound Monday so I'm praying this is our month!