Hi Katie! your symptoms are most likely caused due to the side effects of the Codeine tablets. Generally, Codeine is not used as much as possible, in pregnancy because of the above mentioned effects; unless the pain is severe enough to warrant medication.The following remedies can be tried. Do try a combination of soft tissue massage, bed rest and soothing wet heat alternated with ice pack applications to help calm muscle and nerve spasms. Also pay close attention to your posture, as slumping or standing with a baby on one hip will add to your discomfort. pregnant women with sciatica should always flat shoes or shoes with very low heels. While there is no permanent cure for sciatica, there are several exercises , which can offer temporary relief; such as Williams exercises. These will help relax the muscles that cause spasms. Take care.