By Ellen Chang The balance sheet of CVS Health needs a lot of improvement and investors should be wary, even though he likes the stocks and the CEO, says Stephen “Sarge” Guilfoyle. CVS Health Corp. (CVS) – Get CVS Health Corporation Report has struggled since its acquisition of Aetna and remains a work in progress, Real Money contributor Stephen “Sarge” Guilfoyle says. The net cash position of CVS rose from $10.8 billion to $12.5 billion during the past 12 months and the healthcare retailer has made an effort to pay down its debt levels. The company’s long-term debt fell to $51.9 billion from …