I think the key is not to do too much at once. I used to do 30 mins of Zumba, now that's down to 15mins. I used to swim 50 lengths, now I'm down to 30ish. I used to walk 90mins at a time, now I'm doing 35-45mins. Any injury you get during pregnancy can take an awful long time to heal, so best to avoid doing too much in the first place. You're only trying to maintain your fitness level afterall. I'd rest up until you're fully recovered before continuing to exercise.

If I do not do 20 minutes of stretching at least once per day (preferably twice) I have all of the symptoms you are describing. I also have a back injury, so I know that factors in. I missed a few stretching sessions in the evening and was barely able to do the elliptical the next morning due to hip and ligament pain. I am a bit slower working out now at 33 weeks, but the yoga and gentle stretching make it doable.

There are some good videos on Youtube and Hulu for pregnancy if you are interested. I specifically recommend the 17 minute Gaiam workout on Hulu for low back and hip pan. It literally has every pose that is best and is not too long. You can also google hip openers and prenatal yoga poses. You can find which ones may help ease your symptoms and stick with those. I hope you start feeling better!!

Sounds like you just overdid it this weekend. Rest up and you should feel better soon. As for your back, I suspect that you are doing the same thing I was. I had been over-arching my lower back (letting my belly stick out and pushing my butt out to compensate for the weight out front) which was putting a major strain on my lower back and hips. My back pain got so bad that I wound up in physical therapy. My physical therapist recommended focusing on tucking my tailbone and making sure my shoulders, rib cage and hips were in a straight line.