Etodolac and breathing difficulties

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.