Panadol is safe however if your getting bad headaches try drinking alot more water, i used to get headaches and it was cause i didnt drink enough water (doc says to double your water intake 16glasses a day) when ur preg, i personally can't do 16 glasses but whatever you can do. Headaches could also be related to tension or stress, so try a massage, my neck has been sore for the last couple of weeks (mind you i have a head cold and have done for the past 3 weeks) so im booked in for a pamper package at endota to relax and relieve some tension (just make sure you tell them your preg cause there is some oils they cant use, also make sure they have given preg massages b4, if ur in melb there is a place called baby central i think in dande that specialise in preg massages, havent been there myself but they specialise in preg so they prob more qualified than anyone else)
Good luck and i hope you feel better