Hey mama! At 35 weeks, mild tummy aches are usually normal, could be Braxton Hicks, ligament stretching, or just your baby moving around, pero since you're FTM and want to be sure, better check with your OB just to rule out anything, especially if it gets worse or may other symptoms like spotting or regular cramping. A few of us preggy friends experienced similar mild discomfort towards the end, kaya don't panic, pero peace of mind from your doctor is always best!