I need some advice regarding my 17month Dobie Girl!!

Hi!

This is my first time posting here after numerous searches on this topics and coming up with nothing.

We (My husband, and daughter, age 3, and I) have a now 17 month old Red Dobie Girl named Holly. While Holly is a typical high energy Dobe that gets 2 regular walks a day (2+ miles each walk at a minimum, plus dog park visits) she has had a noted increase in her misbehavior as far as I am concerned. While, in order to get attention she will routinely "Head butt" your legs, she has taken to challenging me (barking with her front legs down, tail wagging the whole time, but also snapping at my clothes and legs). While this behavior has always been discouraged, recently, it has increased to the agressive side. Now by aggressive, I do not mean vicious. She has been backing me into corners (I've had to put dining chairs between her and I just to get away), lunging at me and she does nip and paw my legs, but as I've noted its almost as if she is playing a game.(I have bruises up and down). She has never puppy nipped or even chewed, and this is a fairly recent behavior. While she does this mainly to me, she does do it to my husband occasionally, but never to my daughter.

I don't know if she is bullying me, being the other alpha type female in the house, or if its for attention. We aren't sure what to do as we know it isn't vicious, but we aren't sure on how to attempt to correct this. We have tried everything vet recommended, and nothing seems to be working. She is so smart, but it obvious in that she knows she isn't supposed to do it, because after an 'episode' she strolls right over to her crate for time out. As I said previously she is exercised more than adequately, and I haven't noticed any consistent activity that might be leading to these episodes.

Its making home very stressful as these happen more times in a day than I can count, and I can't bear to continue like this. I love her to death and she is a great dog in everyway but this. Any advice, or similar experiences would be appreciated. Thanks again!!