I hurt my leg - HELP!

About a month ago I competed in a scavenger hunt around the city for 4 hours. I was just starting to get into shape (about 3-4 weeks into C25k). It was mostly quick walking, but toward the end I pulled a muscle in my butt and was limping for a few days. I got into a weird walking routine and had to almost reteach myself to walk for a couple days. When I would walk, it would feel as if my left leg was a little disloacted - it hurts mostly where the leg attaches to my hip.

However for the past couple of weeks it seemed to dwindle as I continued on with C25k. I admit I fell off the wagon a bit and stopped running for about a week and a half. Monday, I got back on the track and continued with C25k as necessary (W7D1) and seemed to have no problem. I left the track feeling fine. After a couple hours, I began to limp terribly for the rest of the night and most of the following morning. I was fine today all day (Wednesday) so I decided to give W7D2 a try. My limping came back almost immediately (on my walk over before I even started my warmups) but I pressed on and was able to get through the usual warmup routine and run about 6-7 minutes until it became nearly unbearable to run because my leg hurt so badly. It's almost like I've conditioned myself to walk strangely in these particular shoes.

Does anyone have any thoughts on how I can stretch my leg out/make this stop so I can get back on track with my running? I don't want to hurt myself - it's still early in the weight loss process for me, and I don't want to get thrown off so soon. I am planning to get myself a good pair of running shoes this weekend (hopefully Friday on my way home from work).