My Husband Has Been On 750mg BId Since December 16

My husband has been on 750mg BId since December 16 2015 due to 2 knee replacement surges 7 weeks apart. I know the anesthesia of both surges and after effects of pain meds can fatigue u for a while. But he recently is so much more fatigued but not sleepy. Can the thin blood from asprin tire u or cause anemia. He is also cold which I know is due to then blood. He's a healthy 61 yr old