Lameness in cats is not common but if it doesn't resolve within a few days of rest it should be investigated by your veterinary surgeon. Lameness may be caused by an injury to a muscle or a sprain - it may also be caused by neurological problems such as a slipped disc. In younger cats one of the most common causes of lameness is a cat bite abscess. The signs in some animals can be very obvious whereas other pets may just become quieter or more grumpy if they are in discomfort.
Physical changes in joints may lead to development of arthritis in later life. Arthritis causes pain and stiffness in the joints. If your pet has arthritis you may notice they are not as keen to exercise as in the past and they may limp or seem to be stiff (particularly when getting up from rest). This stiffness may get better after exercise, and sometimes cold and/or damp weather may appear to make signs worse.