Thank you for your query at DoctorSpring.com
I understand your concern.
Both the drugs ( Cyclobenzaprine and Trazadone Hydrochloride ) don't cause pedal edema directly. Long term use of NSAID's can lead to pedal edema. However since it started happening after the drugs it is better to contact your PCP and wean off the drugs gradually. Though pedal edema is not one of the reported side effects of the drugs, but it can happen as every individual reacts to drugs differently.
I will also advise you to get a routine ECG, serum electrolytes, LFT and RFT done.
In certain mild liver disease cases, for that matter any kind of drug can lead on to pedal edema, if the drugs are not getting metabolised properly.
These test reports will give us a much better insight.
But for the time being, since there are no other symptoms suggestive of cardiac or renal origin, it seems to be due to the drugs, and it will be prudent to stop or switch over to some other drug.