Ay anak, that's something you really need to check with your OB agad-agad kasi kahit walang spotting, severe pain isn't something to brush off sa first trimester, better safe than sorry talaga with your first baby! A few of us moms went through different kinds of aches (round ligament pain, gas, cramps), but kung talagang di mo kaya at affecting your daily life, definitely get it checked out para may peace of mind ka.