Is it ok to put orajel on my toothbrush?

Yes, but?: Why would you want to? If it is that painful to brush your teeth that you would like to put orajel on your toothbrush then you may have some oral problems that need to be addressed. Best to see your dentist to make sure there is no pathology or disease in your mouth. If everything is fine then you can put orajel on your toothbrush if you desire, but put a fluoridated toothpaste on as well.

Yes, but why?: Once per once, orajel is an expensive way to deal with tooth or gum issues. In low doses it will not hurt you but it is not going to help the issue in the long term. See your dentist and deal with your dental issue.