I Have Been Taking Excedrin 4 To 18 Tablets Daily

I have been taking Excedrin 4 to 18 tablets daily for several years for headaches and back pain. I saw something about rebound headaches can be caused from over use. What can you tell me about this. I have seen several doctors over the years for these issues and am now wondering if it could stem from overuse of Excedrin.
I am a flatbed semi driver and have been off work for several weeks now from pain, could it be from the overuse of Excedrin?