Your uterus also goes through alot of growing around 24-28 weeks i remember reading and my baby had a huge growth spurt over this time. It's possibly your uterus stretching and ligaments around it etc.... you did the right thing by asking someone if you aren't sure or doesn't feel right. Better to be safe. I have had period type pains lately but I think it's part of my body preparing for labour which your body would be doing now at your stage aswell.
Glad you're feeling better rest up.