Well fresh track marks are only from 1 thing... Drugs... Cocaine heroin or speed most likely. All 3 will dilate your eyes. They will also appear very glassy. Abnormal sleeping and eating habits too. Severe mood swings. Missing money. Also if he's got tracks then he's got a kit(something to keep his needle,spoon,and dope in) somewhere close by. Long trips to the bathroom. Good luck and I really hope your wrong.
If he has track marks he's injecting something, what he's injecting is unknown but sounds obvious. I can't imagine what else would be injected that frequently. I'm sorry to hear about the situation you're in.