Ouch. Pain left side. ??

So I am cd 24, 5-6 days from my period, and 8-9dpo. This is our 3rd month ttc.

I am feeling a dull ache about two inches down and two inches to the side of my belly button. When I put gentle pressure there, it hurts. Not excruciating, but enough for me to take notice. This has started yesterday, and I mostly notice it when I get home from work and begin relaxing. Any ideas on what it could be? I have never experienced this, debating going in to the doctor??