Hyperkalemia is a common side effect of these medications. GI disturbances, including nausea, vomiting, diarrhea, anorexia can occur. Triamterene and spironolactone have been known to cause impotence and sexual dysfunction. Spironolactone may precipitate gynecomastia or an SLE-like syndrome.
Flexeril has a half life of 18 hours. So 5x18 is 90 hours. Or just under 4 days. Of course, it is not that easy. This varies on how much and how long the drug was taken and it can vary from person to person. That being said I cannot image any way that flexeril would be detectable 30 days after the last dose.
Generally speaking, it takes five half-lives to fully eliminate a drug from your blood or urine. Flexeril has a half-life of 18 hours, so it would take 3.75 days for it to clear out of your body completely. Keep in mind that half-life can vary from patient to patient, so this is not a hard and fast rule. Half-life is also affected if the patient has altered kidney or liver function.