Hi Elaine and a warm welcome to the group.
I totally understand the journey you've had with your IIH, I too started with it while pregnant, but soon got my figure back afterwards yet still had it. I now know it's triggered by my hormones.
I actually managed remission for 6 years, and at first when it came back I just put it down to working hard, that is until I needed a lumbar puncture. It's a bit of a shock when it comes back, you're right when you say how you forget the experience of having it, you get so used to being normal.
It sounds like you could have a low pressure headache, is it better when you lay down, does it make you feel nauseous and like you want to be sick?
The best thing to do is to lie down flat, drink plenty of fluids and caffeine and rest and take pain relief when you feel you need it. Hopefully it should settle down, but if it doesn't get your doctor to come and see you. Sometimes they will do blood patches
to help relieve the headache and symptoms.
Hope this helps.