Ayyy ganyan din ako sa first trimester ko, sobrang nakakaalarma! It could be round ligament pain, super common sa first trimester kasi ang ligaments mo ay nag-stretch na to accommodate the baby, but definitely bring it up with your OB just to be safe, lalo na kung mabigat ang sakit or may spotting pa. A few of my mum friends experienced the same thing at normal lang talaga, but better to get it checked para sa peace of mind mo, 'no?