I suffered migraines out of nowhere before I was pregnant, as well as regular ones in the middle of each month that I noticed when I was on a pill that didn't always stop me ovulating and when I started trying to conceive. They were a great indicator that I was ovulating but a three day migraine doesn't exactly put one in a sex-crazed mood! So the doctors linked the migraines to Oestrogen
My migraines stopped for the first couple of months of pregnancy and then started again, increasing to the point when I was getting three a week and they'd last at least a day. One doctor told me paracetamol, another (I was in the second trimester by this point) told me I could take co-codemol (only risk is the baby becoming addicted too if you take frequent doses), Ibruprofen up to the third trimester and Sumatriptan (Imigran) as this has not been linked to any birth defects once into the second trimester. This, along with acupuncture, helped but I was still getting two a week sometimes and so had to return to the doctors when I was about 22 weeks and reluctantly had to ask for something to help. I now am taking Amitriptyline which is an old style anti-depressant I take everyday. Side effects for me are slight headaches, I wake up some days feeling like I'm hungover and I'm sweating more, as well as just unstoppable crying for the first couple of days but it's more than seven days between migraines now. I have to stop taking them when I enter the third trimester.
Sorry, went on a bit there! Just so frustrated with months of migraines. Even though I've been assured that the medication will not cause any harm to the baby, I still think about it a bit. But I was having so many days off work, because I couldn't do anything but lie in bed. It didn't help that my mum said that if the baby was born with something wrong with it it would be my fault. It's amazing how many people tell you how wrong it is to take any kind of medication when pregnant, but sometimes it is justified and doctors are so careful with what they prescribe.
But OP, you're not alone! And in most pregnancies migraines to stop into the second trimester. Do contact your midwife or GP though as five day migraines sound unusual, even if its just for some reassurance.