Headache Pain at start of Juice Fast

I am on my second day of a juice fast, and I have a very bad headache (which started yesterday) - I did expect this, but didn't expect it be so bad! Yesterday I cheated and took an ibuprofen which took the edge off it, but today I dare not because I know they shouldn't be taken on an empty stomach. But I am in real agony here - is there nothing I can take at all, that would be allowed? I want this to work and am prepared to stick it out, but I don't want to have to lie in bed in pain for days. (As you can imagine, friends and family are trying to get me to stop the fast and take the ibuprofen!) Has anyone any suggestions?