Question

I recently purchased a 1999 528i BMW. I know the history of the car because it has been my moms for the past 6 years, and has been well taken care of. Besides the recent oil change I haven't done anything special to the car. Well about two weeks ago I noticed that the car has started to shift oddly, instead of smoothly going into gear it would stiffly jump. Then the next week, I started to notice a weird idling, it would idle at 1000rmp or so, but the whole car felt like it was shaking, almost like not enough gas was getting to the engine. Now this morning, I started it up as usual to go to work, cleaned the ice off the windshield, and put it in reverse out of the driveway, but when i put it in Drive (automatic) it took ALOT of gas to get it going. Almost like it wouldn't shift out of 3rd gear, which I noticed when i tried to manually shift it, nothing happend. So I looked at the dash and noticed my engine light, and a Yellow gear with an ! point in it. My owners guide says this is a Transmission Control Module, but im unsure what this is. Would possibly getting a transmission flush fix this? or does anyone have any advice on what I could do to fix this problem?? Thanks for any help!