Hi There,
Oh, poor dog! He must be embarrassed to be peeing in the house.
It sounds like your boy has a urinary tract infection. With this there is such a feeling of pain and urgency to go that dogs are bound to have accidents indoors.
A urinary tract infection or UTI occurs when there are bacteria, blood and white blood cells in the bladder. Schnauzers are quite prone to having bladder stones, so that may be the reason that he has this problem. He should be taken to a veterinarian promptly for treatment. He may simply need antibiotics. However, he may need x-rays to look for a stone. Some stones will dissolve with a special food from your vet, others need surgery to be removed.
Here's a link for further information:
http://www.veterinarypartner.com/Content.plx?P=A&S=0&C=0&A=2457
If you can get him to a vet tonight or tomorrow that would be much better than waiting until Monday. Good luck with him!
If this has answered your question, please hit the "Accept" button. I will still be around to answer further questions.
Fiona
Dog Veterinarian
15 years experience as a companion animal veterinarian in British Columbia, California and Ontario