potty training

ok my 3 year old son is already fully potty trained since the weekend after thanksgiving 2017 but the last couple weeks he's been peeing his pants occasionally and peed his pants 4 times yesterday. I dont know what is going on! he has a dr appt today to check for any infections but any ideas on what could be the reasonings for his sudden accidents would be helpful. we are currently ttc and I'm thinking all the baby talk is why he is acting out. what do you all think?