[MC puppies]

We are new to this site and after browsing a few forums most that reference crate training specify puppies.
We have a 7 year old Rottweiler who picked up her initial puppy training like lightning. Sometimes we think she's too clever for her own good.
Over the past year her night times have slowly gotten worse. It started with just whining when we went to bed after she was put in her crate for the night, we ignored it and she settled down after a few mins. Although recently she has started barking and last night we couldn't just leave her alone (we knew we'd be giving in to her but it was 2:30am and she had been barking for 3 straight hours). We thought something was seriously wrong so we wen't down and let her out. She was foaming and had completely covered her mattress. As soon as she was out of her crate she calmed down and we didn't hear a peep out of her for the rest of the night.
We're at a loss as to why this started and how to get her back to being comfortable at night.

 

[Twiggy]

Oh dear. It sounds as if something has really frightened her and she is now clearly very stressed.

Why does she have to be in a crate at 7 yrs old?

 

[MC puppies]

She always has been. When she was younger she got very stressed when she was left on her own and we seemed to be hitting a brick wall when it came to house training. After we got our second dog (a border terrier only half a year younger) she calmed down immediately but by this point she was already crate trained and it was the normal.
We have hardwood floors downstairs where the dogs are and we have tried not crating her at night but she doesn't settle and we can hear her pacing all night (except for last night).