I have severe knee pain help?

i barrel race (several shows a week sometimes) and im pretty sure its caused sciatica(sp??) its like a burning pain from my lower back down the back outerside of my thigh all the way into my knee. It hurts when i sit stand still too long and lay on that side. the only time it really doesnt hurt is when im in the saddle and its been like this since march. i know i need to go to the chiropractor i just keep puttin it off cuz i have vet bills and more important things to worry bout but the severity of the pain went away over the summer for the mot part but its back now is there anything i can do to ease the pain? thanks yall (: