There is no way any behaviourist or trainer can probably diagnose what's going on with your dog from 8 sentences on a forum.
I like to stick to data when getting info from a client. A lot of your description is more your interpretation for the root of the behaviour, as opposed to an objective description of the dog's behaviour (e.g., my dog runs around scared of a stranger, vs my dog backs off, barks, hunches down when a stranger approaches). May seem like a small difference but to a savvy trainer the first does not have information, the second does. There is simply very little information in the post you made.
More info is needed to know if this dog has separation anxiety, but I suspect she has separation issues to some level. If you'd like, we can correspond privately and I can ask you questions and give you information, or you can join my Training & Behaviour facebook page. I would definitely advise crate-training (crate TRAINING, not suddenly putting an untrained dog in a crate all day). Many people start off slow, like 10 minutes, then 30, then an hour, then 2...etc...you want to start off with SECONDS, then move up to 5 seconds over time, then 10, then 20, 30, a min, 2 min, 5 min, 7 min, 10 min, 15 min. Fifteen minutes is an end goal, not a starting point. Think about coddled toddlers whose parents leave them at daycare for the first time. They hit panic in about 3 seconds. They're full blown freaking at a minute. They're not ok up until half an hour after Mommy leaves. You want to avoid the dog ever hitting that place. If you get to the 15 minute mark you're pretty much home free. The worst has come and gone in the first 15 min.
Never ever correct a dog's symptoms of anxiety. The dog is barking, fussing, etc because they are feeling anxious. Correcting (punishing) them for this increases their anxiety, that's the last thing you want. You may or may not get a suppression of the behaviour, but you are mixing up a little mind that needs to be straightened out, not messed up more. Instead of punishing the expression of anxiety, instead, work at relieving the anxiety. Give the dog all kinds of interesting things to do when you leave. Not food; something to eat is gone quickly. Not toys; what are you going to do with a tennis ball by yourself in a crate. A kong with peanut butter inside, a treat ball, a raw marrow bone - something to DO. They will work away for ages at those things. Make sure the dog is getting enough exercise.
Dogs sleep twice as much as we do, about 16 hours a day. You want to set things up nice and quiet for them when you're out, as most dogs sleep all day when we're not home. A quiet area of the house, not near windows, close the blinds, maybe some gentle patchouli reeds, some white noise (TV or radio low, or a fan). And something like a peanut butter kong to lull himself to sleep.