it is indeed hard to tell with young children exactly whats happened but thats no excuse for not gettng to the bottom of it, we can't go giving up just coz things are hard. i think that doctor may have been having an off day, children don't (as a rule) pretend to be in pain and lumps like this are not normal. more x-rays yes, but also pain killers and a diagnosis and a prognosis and some proper treatment. not to mention a bit less of the sending you home with a child in pain and you not knowing whats going on. good luck and be confident, the injury may (hopefully) turn out to be minor, but you are not worrying over nothing here, this does need more investigation. :-)