I wholeheartedly agree with mankylung… You most likely do not need an MRI or X-ray (certainly within the first 6 weeks of pain) but the need should be identified (if there is one) according to previous medical history, neurological signs etc by your doc. They shouldn’t be doled out willy nilly as somewhere around 90% of back pain will end up with a diagnosis of non specific low back pain and your scans will be similar to someone else’s your age, irrespective of whether they have pain or not.
Try not to worry too much about it, keep dosed up and keep moving as much as you can, it should ease up with time and return to normal. If you want to go and see an AHP (Physio/Chiro etc) they should be able to help and provide some advice and treatment tailored to you and your problems. That is the best advice (basically i second everything mankylung has said) If you were in Oz you could come and enrol on our research study!