I'm allergic to all painkillers except codeine and since pregnant I don't dare to take any painkillers. U can try putting an ice pack at the back of your neck and lean back, the cold will help with the headache.
Never attempt to self meditate. Best is to seek your gynae's advice. Drinking lots of fluids also helps. During pregnancy your body needs much more fluids so drink up at least 2 litres daily.
It is better to check with doctor since you have allergy