Am 17 weeks pregnant with dc3. Since week 12 when my exhaustion and nausea stopped I've been given the gift of permanent headaches (often accompanied by sickness). They don't let up and last about a week. I get a reprieve for about a day then they crank up again. I had migraines in previous pregmancies but it wasn't a constant thing. Any ideas what's causing it or how I ca shake it?