19 weeks pregnant and have a sharp constant pain in lower right side of back what could this be?

Several possibilites: At 19 weeks of pregnancy, you are likely starting to feel normal aches and pains. Low back pain and 'round ligament pain' are common. With what you are describing though, the possibilities might also include: 1. Pain from the right ovary 2. Apppendix related pain 3. Kidney stone 4. Kindey infection you should contact your OB provider to get checked out! good luck.