Unfortunately she was probably given too much trust and freedom too early. 5 months is still very young to be housebroken.

You need to start all over again as if she was a new addition. Obviously you can't trust her alone for 5 minutes. So it's back to the old routine : go out every hour, 10 minutes after every meal, before bedtime and when getting up.

If you have to go to the bathroom, she goes with you or she goes in the crate. Never leave her unattended on furniture, even for 30 seconds. Remember, everytime she has an accident, it's your fault for letting it happen. It's not her fault, she's only a puppy. Also, every accident means you start all over again, and every bit of freedom that was gained was given too early, so you take it back and readjust.

One more thing : make sure you rule out the possibility of a urinary tract infection or other condition. If that's the case, she needs medical attention. Although from your post it seems from typical puppy drawback when given too much freedom...

Good luck.