Dog suddenly scared and don't want to leave the house

[gugll]

My dog is some 10 years old, male, mixed breed long haired terrier like and was always active/vivacious and friendly. Since 4 days ago he don't want to leave the house, he is scared and is shaking if I bring him outside the house. When in house he mostly sleep. He is eating normally and doing his "duty" when outside.. but then he is walking 50 cm from me and tend to return home.
Last days was mating time for him and in place where we leave he is able to leave the garden and we are trying for years to stop him doing that but unsuccessfully.
I made little investigations and so far seems he was scared by other (female) dog owner.. while mating. I don't know what she did to him and thats not 100% sure but I'd say thats what happened.
I need some guidelines what to do now. Should I leave him sleeping for few days (in 4 days situation changed to better but very very slightly) or should I take him out even if he don't want to.. to teach him again not to be scared.. When outside he sometimes get so scared that he scream.
Thanks for any kind of help.