I've Been Prescribed 50mg Dicloflex And In The Past Advised

I've been prescribed 50mg Dicloflex and in the past advised to take this with 5mg Diazepam for lower back pain with fairly regular painful spasams. I've read that the effect of Dicloflex is cumulative. I'm just wondering how long it's safe to take Dicloflex and also if there are any issues with taking the combination of Dicloflex and Diazepam