A.K.
I think this is totally normal! He is getting older and wiser. He is testing you. Yes even 13 month old babies know that they can test their parents. How many days has he been doing this for? Is he finally falling asleep? If so, for how long? It could be a number of things. He could be teething, going through anxiety, testing you and your husband. Have you tried giving him something for his tooth aches (Tylenol or if you prefer homeopathic medicine)? Every time my daughter would get a tooth I would give her some type of relief. She would sleep much better, but still would struggle during the night time. If you see some sign of relief, then you know that he is teething. I would say that if he is finally falling asleep and staying asleep then it isn't an ear ache. You'll know if your child has an ear ache. They don't sleep and they scream all the time. They tend to grab at their ears as well. If it's anxiety, you can try comforting him. This all depends on what you can handle or prefer. If you think you can handle hearing him cry then I would say do the "cold turkey" method. Just let him cry it out. It will only last for a week or so of crying, but then he'll learn to soothe himself back to sleep. If that bothers you, then comfort him. Rock him, sing songs, rub his back.
Good luck and hope you figure out what the problem is!
ak