You can eat all of the salad and yogurt that you want (which is good for you) but you will not lose weight unless you eat less calories than you burn. You have to make sure you are eating enough, but not too much. It is a delicate balance.
Your bowel habits WILL change when you change your diet. That is natural. Go for a checkup if you feel you must, but it is a normal thing if you go from a meat and potatoes diet to one containing much more fruits and veggies and less junk.
You also have to give it some time. You cannot expect to do it in just a few weeks. You didn't put the weight on in a couple weeks, you can't expect to lose it all in a couple weeks.
Shopping for good food doesn't have to break the bank either. Shop the sales. I buy my produce based on what is on sale for the week-this week in my flyer cantalaupes are $1 each, nectarines are $1 a lb., and bagged salad is $1 each, so guess what I will buy when I go?
Shop smart, and it will be fine.
If you tore a muscle at Curves last YEAR, then it really shouldn't be a factor now. You should be sore after a good workout, but excrutiating pain you should not feel. If you are still having pain in this area, go see a doctor. If not, get back on the exercise wagon, and don't let the fear of injury happening again keep you from exercising.
You sound like you are at a very crucial point-one that all of us who have lost weight have went through. You are at the transitional stage, where you want to lose weight and are close to making the mental connection that you need to change your life, but fear is holding you back, and you are making excuses for not doing what you should be. It is a lot easier to talk yourself out of eating better and exercising than to just get up and do it.
I am not trying to be hard on you, I have been where you are. I had to work through a physical injury myself, and I have. I just think that you have to be ready to do this, and if you are, start saying positive things to yourself, rather than trying to talk yourself out of it by listing all of the reasons that you "can't". If you think that you can't, then you won't. If you change your mindset and say "I CAN" then wonderful things can happen.
Good luck to you,
Aphil