Should I go to the doctor right now? I scratched my testicals and they stared to burn for 30 seconds and now there is a blister there help!

Unless . Unless the area is red, inflammed, painful, or you have a fever, i don't think a medical visit is necessary. If those symptoms are present then you may have developed a secondary bacterial infection that needs treatment. Are you sure the blister was not there prior to the scratch? If so, then that raises concern for herpes. If this is the case then a medical evaluation is in order. Lastly, if the blister has resolved and it returns this is also a reason to have a medical evaluation. Good luck.