38 weeks on Saturday and for the last couple of days I've really been struggling with what I thought was a head cold, however despite drinking literally litres of water through the night I have woken this morning with a headache, dried sinuses, chapped lips and a raging thirst I can't quench, I thought it was maybe just the weather and central heating but now I'm wondering if I should speak to my midwife or if this is a common side effect In late pregnancy?