I had a severe headache 1st and 2nd day along which?radiated to my neck and shoulder. Also, experience very dry mouth; I did drink lots of water, but still didn't help. I really want to take this medicine because of the cost. I got a card from my doctor where I can get it for $4 a mo. Today I halved the tablet as I was afraid a whole one is too strong. Blood pressure is 134/84 which is ok, but higher than normal. Should I continue to take it?