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Hi there. Thanks for the question. I am sorry to hear that Rain sustained an injury. Let me see if I can help.
If Rain is able to walk and jog normally then it may just be that he tweaked his leg while playing or perhaps his knee or hip based on the fact that you said he had some trouble lifting his leg sideways. Do check very carefully for any broken toenails or injuries between the toes. Otherwise...try to have him rest for 24 hours. No running jumping or heavy play (I know thats hard with a young dog) but do the best you can. If he is still significantly painful in 24 hours (or after this weekend) then get him in to see a vet.
I hope this helps. Let me know if you have any other questions.