Cyclobenzaprine (Flexeril) is not a sedative drug as far as I know. There is another drug that was historically indicated for all of the same conditions known as Carisoprodol (Soma), and a lot of people often assume that the similar indications imply that the drugs are similar. The latter is actually a potent sedative with characteristics of a Barbiturate.
Cyclobenzaprine is also a muscle relaxant. It differs in that it doesn't produce sedation and is much safer than Carisoprodol. Taking Opioids with Carisoprodol is likely to knock the person out and high dosages can easily be lethal.
You will be fine. just be responsible as you are being and you will be just fine.