The burning sensation you are experiencing is likely heartburn, which is very common in the third trimester. For safe, immediate relief, you can try over-the-counter calcium carbonate antacids. Lifestyle adjustments, such as eating smaller meals and not lying down right after eating, also help. If antacids do not work, your doctor may suggest an H2 blocker like famotidine. Please consult your OB/GYN before starting any medication. Note: If the pain is severe, persistent, or accompanied by headaches, vision changes, or swelling, seek medical care immediately to rule out pregnancy complications.