my 13 year old was feeling ill, woke up to go to bathroom still half sleep. Felt dizzy leaning on sink then passed out and fell back onto closed bathroom door. Grandfather heard fall and she woke up to his voice and got up. her back is hurting from muscle strain, not bruising or abraisons. just muscle pain in upper back, increased pain when she moves. grandpa want to give Flexeril 5mg. is it safe. needs pain relief just to get comfortable enough to try lying down to sleep. strong pain when coughing or just trying to get comfortable in bed.