My bird is walking funny and very weak, any suggestions?

As answered below, your bird could be female and trying to lay an egg or is egg bound (egg bound means the egg inside the bird is stuck inside and the bird can not get it out, the bird can die). Whether or not this is the case, birds mask illness so by the time you may realize that they are ill, they may be very ill. Please take your parakeet to an avian vet as soon as you can.