39w4d pregnant, stomach ache that won't go away...?

I woke up from a nap with a tummy ache so I used the washroom, ate some tums, drank some water and 4 hours later its still there :( I have no signs of early labor at all just cramping here and there, I had a prenatal on monday and I'm not even dialated or anything like that. I'm a first time mom so I have no idea what's going on...