My legs ache when i use them to much or not enough, if i bend them eg. squat, sit on certain chairs, cross my legs. what's wrong with them?

Myalgias: Myalgia or muscle pain/aches can be due to many reasons. Poor conditioning and overuse, lactic acidosis after vigorous exercise, partial tears, trauma, etc. It sounds like your problem is positional and may be related to a circulatory issue. Women and men are both susceptible to vascular disease. Try an exercise regimen to strengthen your legs. If pain persists see your physician for an us.

Many reasons: It is normal for the muscles in your legs to ache after excessive use, ie exercise. That is normal response. If you have pain at rest, it may represent delayed onset post-exercise soreness or other sources of myopathies. There are specific diseases that can cause muscle soreness as well as some medications. It is best to discuss this with your doctor.