I have experienced that type of headache only once and my chiropractor told me that it was a "tension headache". You might want to go to the doctor if it is very severe, to make sure that isn't something serious. Also, have you stopped taking the herbs for the day? It might be a good idea.
You can go to the healthfood store and get a good brand with an antibiotic/antiviral combo.
Sometime ago when I was doing a lot of research, I came across an article about parasite die-off and how they can sometimes cause tissue inflammation and pain. Of course, they prescribe a cortisone. There are herbs that have cortisone properties - bupleurum, licorice and ginseng. You can get all three or one. If I had to pick just one, I'd go with buplerum based off the studies I've read and it's also a good liver cleanser.
It may help you out if tried a Google search on herbal cortisones. Someone suggested red clover and drinking lots of water - those are good ideas too.