I just filled a prescription for Etodolac which I'm supposed to t...

I just filled a prescription for Etodolac which I'm supposed to take for one week. The purpose is to try to alleviate inflammation on my knee. I took only one pill yesterday, skipped the pill last evening because I hadn't eaten. This was my FIRST and only Etodolac pill. This morning I awoke with a really bad headache - the kind that starts across your shoulders and works up the back of your neck until it's stiff and your entire head hurts. I've had these before, but not for a long time. Could it be from the Etodolac? I'm afraid to take another one.