Your body may like the weight it is. You are very tall and that is a good weight for that height. Weightlifting builds muscle and it weighs more than fat, you may be perfect. If you are unhappy.. you may just need to tone. Which you probably already know.
As far as what caused such horrible side effects.. I'm not sure. Why don't you post what you ate on most days and we can see if we can help you more.
About low-carb and athletic training.. im still reading and learning about that. When I get to goal weight I will be long distance cycling and also do not want to bonk. There are some very good threads on this forum by people who cycle that have some great info on carbs and training.