My leg hurts and is constantly cracking, is this normal or not?

I'm 31 weeks, 4 days pregnant. The cracking started out in my right foot a few days ago, I cracked it to relieve the uncomfortable feeling but it got worse every time I did. Eventually, it started to be painful and now this crack-relief painful feeling has traveled all the way up almost to my knee, traveling so fast just today. Is this a normal part of pregnancy? It's my first time so I'm not really sure if I'm just being paranoid or whatever but it's extremely uncomfortable. Any ideas? I need to feel at ease. Thanks!