My mom had this problem with a pom… First when people came over we told them to totally ignore the dog, no eye contact, just act like he wasn’t in the room. We would give the guest some dog treats so if the dog became curious and cam over to sniff, the guest could hold out a treat, still no eye contact, talking or touching. Soon the dog felt better about coming over to strangers and then if they would let them pet him he got a treat! After doing this for about a month he was sooo much better about letting guests touch him.