I agree with OytheGreat....... this might just be temporary since, your body has gone through some changes.
You might consider have your thyroid levels tested, since hypothyroidism is a major cause of sudden weight gain/inability to lose; however, you aren't overweight by any stretch of the imagination, so you might be okay to wait a couple months and see if your hormones balance out again .
I recommend that you keep a food diary and count how many calories you are actually eating/day. If you aren't taking in enough, your body many hand onto fat stores already there to prevent starvation.
Yoga is usually very good for toning muscles, and helping to get rid of fat; maybe you need to either change up your routine or increase the intensity, if you can.
It's always best to give both your diet and exercise routines, variety; otherwise, the body becomes used to the same things every day, so nothing is a challenge anymore.
With all the recent changes in the body, it may just be a temporary issue. Hormonal problems can cause weight gain, water retention, etc. So don't sweat it out unless a couple months have passed and there are no changes.
Otherwise, you might check how many calories you're consuming. You may be cutting too much or eating a tad over what's necessary. I tend to think this is just a temporary issue, however. You dropped 4 lbs in two weeks already. The rest will come with time.