Injury & Tip Toe Walking

My hubby & I are wondering why our daughter would start doing this behavior and if there is something we should be looking into?

in a nutshell:

She recently turned two.
She was hanging from monkey bars and fell straight legged (knees locked) with a thud about 10 days ago
She had a slight limp which developed into a more sever limp.
She would not put pressure on her left leg.
We x-rayed, etc...nothing
A few days later she refused to put pressure on the right leg, thinking we may have x-rayed the wrong leg, we took her back to the doc, they decided it was maybe in the hips and took a hip x-ray....nothing wrong showing
She then could no longer bare weight on either leg and would fall if not supported...so she started to crawl.
All along, unable to tell us of any pain.
We took her to a pediatric orthopedic surgeon specialist Friday and he has requested a bone scan for Monday
Today (Saturday) while we wait, she started to walk sturdy as can be on her tip toes, but can not place her heels down without falling to a crawl position.

Why would this tippy toe position be easier for her then normal walking?
Could she have a neurological issue from spine damage?
Could she have Guillain Barre Syndrome that just happen to come around at the same time as the monkey bar fall? (someone suggested her decline in walking ability might be GBS, but so far the doctors haven't considered that)

[MotherofActiveOnes]

UPDATE ~ turns out she broke both heels and it took 3 weeks, 3 different doctors, a pediatric orthopedic surgeon, several x-rays & a complete body bone scan to figure it out. And by the time they figured it out, she was already healed enough to withstand some pressure and they suggested letting her finish out the healing without casts, but if she started to limp or refuse to walk again, they would put her in casts or special walking boots...it's been a few weeks and she's fine and back to normal.