Etodolac side effects

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.

I have alot of neausa and diahera since taking this medication.I not going to take it any longer....

heart pounding, difficulty breathing - this occurred after being on Etodolac for 7-9 days, 2/day.

Last year, I was prescribed Etodolac for pain I was experiencing in my knee. After incredible improvement in my knee within 24 hours, I continued taking Etodolac. After 7-8 days on Etodolac, I started waking up in the a.m. feeling like my heart was racing and difficulty breathing. I thought I was coming down with flu or pneumonia. Went back to dr., who additionally prescribed an antibiotic. Symptoms continued until I read about the "rare" side effects (breathing difficulties, congestive heart failure, etc). I called my pharmacist Sunday morning, who advised me to stop taking the Etodolac and see if symptoms improved. I stopped having the pounding heart (which occurred 9-12 hours after each dose). I called my dr. the next day to make him aware of my reaction to Etodolac. However, I'm wondering if it could have done any permanent damage. I found out, during a routine colonoscopy that I had a heart irregularity and ended up having to have a pacemaker.