What do we do when our 2.5 month old puppy goes insane and bites us?

Our half rottie puppy was taken too early from her litter and we just recently adopted her at 2.5 months. Her bad biting behavior has been severely escalating in the last few days, biting us to the point that we are bleeding. For the most part she is really good except in the following 2 situations:
1) when we take her out and she gets to the sand (we live on a beach) she will start digging and then going nuts and growling and pouncing on our feet and ankles and biting them HARD. We try to distract her with toys or by having her sit and then praise her but then she'll just start right back up again.
2) When we carry her back up the stairs from going out to the bathroom (she's not big enough to climb them herself) she'll start snarling and biting near the top of the stairs. We try to settle her down and wait until she calms to put her down but sometimes she just goes insane and bites and growls like a little psycho

We live abroad in Panama so puppy school isn't an option!! Help!!

Asked by Member 1041387 on Jul 18th 2011 Tagged biting, ankles, agression, puppy in Behavior & Training