I would trust your gut and get checked out. You know more than anyone else for yourself when you don't feel right, and it certainly sounds like you're there. Your peace of mind is completely worth a call. Here's hoping it really is "just" heartburn, but if it's not you want to know ASAP.
2008-Our Baby Girl, PTL born too early at 30w6d, Fought so hard... Forever Loved & Missed
2010- Lil' Bro, Pre-E at 29 weeks... Induced at 36w6d, Born 37w
2012- Lil' Sis, Super-imposed pre-e at 25 weeks, PTL & GD at 35 weeks, Evicted 36w