Does sound like a bug on your stamina or you where just drain down when drauger appeared. But walking away in water or on land, stamina should have came back up. Only reason it may not have , is if you have low food health points which results in low stamina bar. Better the Food, More stamina bar grows.

Sounds like you found a Drauger spawn bone pile in the swamp, until the bone pile is taken out, I use sword to take it out, you wont have a chance. I would make up some stamina, poison potions and the best arrows and bow you can make at this time of your characters level and take out the bone pile with arrows from a distance, then clear anything left over.

In future reference, I try not to take on Draugers with hand to hand combat, I use bow and arrows while I "Run Forrest Run" and bob and weave. LOL