Well, if there are yellow stains on your shirt, he's probably peeing in there. What you need to do is make the crate smaller. He will not pee in there if you make it small enough. It needs to be so small that when he lays down he touches every bit of the floor. You can do this by putting a cardboard box in the back or books or tupperware or something like that.
As far the still peeing in the house, he is still VERY VERY young! It takes most yorkies a long time to be potty trained. I would not expect to see any real results until he is AT LEAST 6-8 months of age. When he is not in his crate, you need to watch him like a hawk! If you are not able to keep a VERY close eye on him, he needs to go back in his SMALL crate. Take him outside to potty every 2 hours, everytime he wakes up from a nap, everytime he gets done playing, and about 30-45 minutes after he eats or drinks. The key is patience and consistency. Give him a treat and really praise him when he potties outside. If you catch him pottying inside, then you need to tell him NO in a very stern voice and take him right outside. He will eventually get the hang of it.
I definately would NOT switch methods on him at this point. That will confuse him and just make it harder for you to potty train him. Stick to teaching him to go outside.
DO NOT GIVE UP! He is so young! You can do it! Just stay positive!
