I have started some upper body weight-lifting in the last week and I have a couple of questions.

1 Why do my muscles feel so weak? It feels hard to even lift up my arm after doing it and even for a day or two later.

2 I have done weight lifting a few years ago and it never felt this hard on the muscles. Does the LC have something to do with this?

3 Don't you have to have carbs to build muscle or is protein good enough?

I only do about 5 exercises of 3 sets each at 50lbs
and when I'm doing it it feels ok it is after and the next few days
I give a day in between for the muscles but I don't feel like doing it again till three or four days and I wonder why? Sometimes even doing household chores my muscles feel weaker.

Any advice would help

Thanks
Sandy

Your muscles feeling weak for a couple days after lifting is normal. As you adjust to lifting this might go away a little bit, but the fact that it happens means you are pushing your muscles hard and it will bring progress in the long run.
However, it sounds like you are lifting your whole body at every workout. You said you don't feel like working a body part again until about 4 days later... that would actually be a good thing. Lifting is the stimulus for growth, but muscles only grow between workouts. I hit each bodypart only once per week. But I don't recommend that you start with that. I would recommend spliting your workouts into upperbody one day, lower body the next. Then take a day or two off.
You should give your muscles at least 2 or 3 days off before working that muscle again.
You don't NEED carbs to build muscle... your body will eventually adapt to lifting with low carbs. But it might speed up the process if you start adding occasional carbohydrate meals. I use the NHE plan. You can find information about various plans (such as TKD) on this forum.
Check out: http://forum.lowcarber.org/showthread.php?t=190999
Good luck!