Am i allergic to flexeril, benadryl, and most PM drugs?

Am i allergic to flexeril, benadryl, and most PM drugs? I have scoliosis, a bulged disc, and very mild arthritis in my back, but the pain can get to be unbearable. my muscles are so tight and knotted that it can leave me in tears (20 year old male). i have been taking flexeril for a year, and i have only used two bottles (60 10mg tablets) however, when i took one two nights ago, i began to shake and get very cold. following that immediately was immense pain in my chest, and extreme pressure going against my breathing. it was all night long until i could breath normally, i was so light headed from panting that it made me nauseous. my lungs felt bruised and three days later they are finally getting better. i also went numb in my hands, feet, arms, calf's, and i had pain shoot down my arm once or twice. im terrified to ever take it again, it was extremely painful and scary. When i take any type of pm medication to help me sleep (because i cant due to the pain and discomfort) it wires me, and causes me to become jittery, so jittery i feel like ants are under my skin. is this also an allergic reaction? It does not happen with anything else but flexeril, or pm medication. i have Kaiser, they have never cared to look into my problems, even though i come in almost once a month, they just send me out saying i need to posture up, and go buy an inversion table (would love to, cant afford it) obviously i need serious help. can you help me with the right answers? what should i do??? what medication should i ask my doctor about?