If you need a precription drug, I wouldn't stop taking it without a doctor saying it is okay, if it is for something very important. I don't know if it will harm your fast, but I don't think so.
However, eating a cracker is going to cause harm to your fast. It will start your digestion back up and slow your detox. So try not eat - which is very hard!
As far as weight - I've lost 45 pounds total from my highest weight. Of that I lost 17 pounds on a vegan diet over about five months. Then I lost about 9 pounds in three weeks on a raw vegan diet. I've lost 19 pounds in 39 days on the juice fast. I haven't cheated once, either. I've gone from 175 to 130 - and I'm 5'4".