Gosh, your bike sounds like mine about a month ago. I was in and out of the shop so many times that the mechanics were practially laughing at me. Anytime they'd see me, it was like "what did you break now?" In two weeks I had to replace the following-
1. The chain. It broke smack in the middle of an intersection about 2 miles from home.
2. Of course, it took the deraileur with it.
3. While at the shop, the mechanic decided he should just replace the grip shifter while he was at it. It had cracked somehow. Luckily he had a spare one of the right kind floating around and he gave it to me for free.
4. Then, a week later, I noticed that the side wall of the front tire was frayed. It was original to the four year old bike, so it was about time anyway.
5. At the same time, i noticed that one of the spokes on the back was broken. I took it in to the shop to have a new spoke woven in. When they started doing this, all the other spokes started snapping, so I had to buy a whole new back wheel. And a new cassette too. The old one was kind of worn I guess.
6. And, last but not least, they noticed as they were mounting my tire onto the new wheel that there was a cut in it. I guess it must have started small, but it was getting bigger. So, new back tire. At least I have all new tires now.
7. And then a few days later, I had brake problems. New back shoes, new front cable and adjustments all around.
But, nothing else has broken for a couple of weeks, so far, so good. I figure with a lot of this stuff, it was about time. It was original on the bike and I didn't really start taking care of the bike until this year.
I should go now though. I have to leave to get to my bike repair class on time...