First month on bc question

I really could use some advice ladies! I have had 2 miscarriages this year and the last one being in June. I had my first period last month and started birth control after. I am on the last week of pills and I know your period can be weird the first pack of pills but from what glow says I am a day late. That's fine but today I woke up and have the sorest legs and butt. I haven't done anything different for this to happen. I was wondering If anyone had this symptom as an early pregnancy symptom?