Extreme lethargy, exhaustion, difficulty concentrating, occasiona...

Extreme lethargy, exhaustion, difficulty concentrating, occasional dizziness, headaches after taking Warfarin for 4 months, average dose 7.5 to 8.0mg daily; doctor and nurse said NOT a side effect of Warfarin, but when I stopped taking it for a week, the symtoms went away and my wife saw right away that I was "back to normal". Doctor and nurse said problems might be due to Tramadol I was taking at same time, but when I stopped the Tramadol for two weeks, there was no change. I am very upset that these very upsetting and distressing side effects of Warfarin are not stated. I know of two other cases similar to mine in the UK.