Don't try to comfort her - you'll make it worse
All dogs go through a series of fear imprint stages in their lives. Which is extremely logical, if you think from an evolutionary/wild living perspective. The first fear stage is very brief (a couple of weeks duration) and occurs around 10 weeks of age - right about the time that pups are gaining a bit of independance from their mothers. Thus, a darned good time for them to learn to be afraid of some things.
The second fear imprint stage occurs somewhere between 6-14 months, and usually lasts around 3-4 months. Also perfectly logical - in a natural environment, this is probably the age at which pups are learning to take on some responsibilities in life (hunting, pack guarding). And realising that they need to be wary (or outright afraid) of some things is rather important.
Some dogs go through a third fear imprint stage a little later.
Anyway - that's
why many adolescents are noticably fearful around this age. Of course, it varies from dog to dog just how noticable it is - for some it's barely discernable, while for others there'll be a fit if the trash can gets moved.
As for how to deal with it... do NOT try to comfort the dog. If you do, you will simply confirm that she was right to be afraid of whatever the scary thing was. Same if you try to force her to face it. In fact, any time you make any sort of fuss at all, you will achieve no more than reinforcing in the dog's mind that whatever it was they thought scary was indeed something to be wary of.
This is the time that they are looking to their pack leaders and elders for guidance. And if you make a fuss, then obviously, there was a reason for the fuss (in the dog's mind) - therefore, that object/situation is something they will continue to be scared of. If, on the other hand, you take no notice whatsoever - you approach every situation in a confident and upbeat manner, paying no attention whatsoever to the dog cowering behind your legs... well, that sends a clear signal to the dog that there's no reason to be hiding behind your legs

If you, the leader, are not the remotest bit concerned about the garbage can that looks scary, or the guy ahead you've got to pass on the sidewalk,
the dog will notice, and gradually follow your lead. Doesn't mean she'll stop being scared of everything overnight - but in time, she will learn from you that each thing is not a threat. And at the end of the fear stage, a confident and outgoing adult should emerge.
It is very important that you lead confidently. It's not just about a timid dog. Timidity can sometimes lead to a defensive dog - one that bites out of fear. So it's very much worth your while to invest the time and effort in
showing her through your own confident, outgoing and nonchalent attitude (basically ignoring her fears) that there is nothing in fact to be afraid of.
More on the various stages of development that pups go through at
www.boxerworld.com/puppy/education