Small fractures don't always show on x-ray and often don't show on x-ray especially in this type of problem. Stress fractures, spondylitis etc. won't show at all on x-ray. These need more investigation like a bone scan or Wikipedia reference-linkMRI

On late stage ones will show. You, your coach and your sports physio need to take a look at your action and especially you follow-through to see what's going on. Not that rest makes a lot of things seem better but their cause remains. Best to look at the reasons why now if you are serious about developing cricket to higher levels. Good luck