Hi Mam /Sir
Children usually fall while they are learning to walk and fortunately most of the falls while walking lead to minor injuries. They heal spontaneously and do not need any treatment. Small injuries do not cause fever. The fever is most probably a seasonal viral fever which is being seen in many children. Pls read the article on fever in practo health feed below.
Next Steps
"My Child Has Fever! What to Do?" by Dr. Sreedhar RS - https://www.practo.com/healthfeed/my-child-has-fever-what-to-do-25940/post
Health Tips
Pls see a Pediatrician if he is not doing well