get a test kit for ammonia nitrite and nitrate.
normally adding a shrimp is to get an ammonia reading, but since you have die off on the live rock i am not sure if you still need to. If you have a ammonia reading of 3.0 to 5.0 that is a good thing and will help you have a strong bio filter. i have read posts from people saying they have a small reading like 0.5 or less and think thats a good thing. A low ammonia reading only means you will have to add fish much more slowly, but if you have a higher reading the bio filter will be better and able to handle more fish at once.
anyways, get those test kits so you know where you stand.