Hi, Maryann!
A big problem is the use of those strips. In the first place, they're notoriously inaccurate. Secondly, the colors can bleach out if the chlorine level is too high. For all you know, you're at twentysomething free chlorine. It's just as reasonable as saying you're at zero, given the strips.
Second problem is the use of dichlor "shock". Going generous, let's say your pool is a rectangle 16x32x6 feet average depth. That puts it at 23,000 gallons. 30 lbs of dichlor has raised the CYA level to 79. In reality, the pool is probably a lot smaller so the CYA is going to be a lot higher. Just to keep algae at bay, and not necessarily get ahead of it, will require a FC level of 6. Shock level -- enough to kill things -- is 31. The reality is the CYA is higher so the minimum chlorine is also going to be higher. You're caught in an endless spiral using dichlor. Each time you add chlorine, you're raising the minimum FC level you need. At this point you need to stop shovelling money into the pool and start spending it wisely.
First step is a proper test kit. Do not skimp. The K-2006 is okay, but it's skimpy on reagents. A better buy, despite the higher price, is the
TF100. Spend the extra on the XL option as well. Without a proper test kit, you're working blind. It's like trying to paint with a blindfold on. You might get paint on the canvas, but all you're really doing is wasting paint and ruining a canvas.
Step two is to replace the pool water. You're going to be loaded with either CYA or Ammonia, and fresh water is going to be cheaper than the chemicals. With a vinyl liner, you never want to remove it all. So drain it to about a foot left in the shallow end, refill, run the pump a day, and repeat. Then get some test results and we can guide you. There is no shortcut.