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You need to take him in so the can evaluate the urine. This loss of control is alarming and can be due to an infection or something more serious like diabetes (although he is young). I recommend an appt as soon as possible so that the appropriate medications can help. Infections can increase urgency and accidents...the infections can be present +/- blood.
If the dog is in heat that definately can be the problem...
but neutered dogs tend not to mark very often...especially if they didn't in the beginning.
If the dog is in heat it shouldn't be in your house..if it is a little puppy...I still think a vet should rule out an infection, mainly because he wouldn't urinate in the bed while sleeping if there was no problem.
I can't recommend the use of the medication unless an infection is present. If you have a vet established, you can take the urine sample in and have it evaluated. An average urinalysis runs about $20.