nicgirl, I am so sorry that you are feeling a little down in the dumps!! Chin up!! You have done an awesome job, and don't think that you haven't!! You are more than half way to your goal!!! That is impressive!!
I have been taking magnesium supplements. The tablets are 250 mg, and the bottle suggests one tablet a day, but because of the constipation problem that I have, I have been taking 2 pills at lunch time after I eat and it is working wonderfully. There is no cramping or bloating and I am very happy with the results so far. I got them at Walmart, but have also seen them at Walgreens and they would probably be at any nutritional store. They were about $7.00 for 100 tablets, I think, so not really expensive either.
Have you tried zig zagging your calories and exercise? That is usually what it takes for me to kick my loss into gear again. I am losing pretty good right now, but that is because I have recently gone back on after being off that 30 days, so it usually does work better after that. And I have really been kicking the exercise up a notch, too. Nothing fancy, but things that will get my heart pumping for at least 15 minutes every day.
Don't let this little bump in the road throw you off course!! There have been a few times when my loss has been at a stand still, too, so you are not alone, there! I was swearing to my husband that my scale was broken for about 3 weeks because it barely moved....he finally stepped on it to prove to me it wasn't the scale! lol!

He's such a stinker sometimes! lol! So, believe me when I say that I really do understand! Try changing things around....change your calorie intake every day, change your exercises, not just what exercise you are doing, but when you do it and for how long. And to be honest, if you are having a big problem with the constipation, it could be the source of not losing, too.
Hang in there, I just know it will get better for you!!! You have to pull your belt in another notch and push yourself as best as you can!!
Keep us posted on how you are doing!! And, by the way, I bet your dr will be thrilled with what you have accomplished so far.....don't look at the little things....look at the BIG picture!!!
***HUGS TO YOU!!!!***