my avocado tree went into shock
I transplanted it from a one gallon pot to a five gallon pot, then it went into shock.
If you potted up from a 1 gal container to a 5 gal container, the new container is really too big. This means that the soil is staying too wet, and the roots are being slowly drowned. I think if you can take your avocado out of the 5 gal pot and put it into a smaller one then proceed as this article suggests, you may be able to save it: https://www.gardeningknowhow.com/houseplants/hpgen/repotting-stress-treatment.htm