Taking aspirin for a month to prevent clots after a leg injury. i know it can cause reye's. what are the signs i need to watch out?

I wouldn't sweat it: The link with Reyes syndrome was primarily in kids from early childhood to the early teens, and as a followup to flu or chickenpox. Since this doesn't apply to you,I wouldn't worry. Reyes was heralded by sudden deterioration in a kid who was healing. They would go into a coma and often never live to come out of it. Their liver would fail and death would ensue, often within days.