rabbit pee

I have a 6 year old male dutch rabbit. He is usually very calm and likes to play but since 2 days ago he has been sitting in his cage all day and not being his usual self. This morning he peed inside his cage which is new since he usually uses his litterbox. He has also been making very soft...

So recently we got a new rabbit and my mom accidentally touched the pee. The pee was red. She said that the area where the pee stung. Is this dangerous? Should we get her to the Doctor?