I was sleeved on 12/28/17 my doctor held off on my exercise because I was extremely lightheaded but I have been doing cardio now I'm trying to add in weights and my muscles are extremely weak my leg actually gave out one time and I fell is this abnormal should I be concerned??

try to keep in mind you are probably taking in a lot less calories than your body is use to. This mean you are now forcing your body to use the fat stores that your body wants to keep for lean times and emergencies. If your like most of us you have had some time of lack of exercise as well, which can lead to some muscle breakdown and weakness. Make sure you are getting in enough protein so that your body does not try to break down muscle for fuel, that should help, and if you continue to have concerns talk to your doc, that is what they are there for.