I have upper back pain on left hand side which is greater when i lie down. feels like internal pressure pain. i'm constipated and have head aches?

Taking narcotics?: I am assuming that the back pain and headaches came first and the constipation followed... If that hunch is right then I am going to assume that your medications include some opioid like vicodin. This would certainly cause constipation and is a poor choice for either headache or chronic back pain. If you have not already done so, consider seeing a spine specialist or neurologist for back and head.