Long white "stringy" feces is a common problem associated with internal parasites. These parasites affect different fish differently so the pale complexion could also be cause by the parasites. The solution is actually simpler than you might think, food.
Pay a visit to your pet store and pick up some parasite food. There are several brands, all good but I'm sure some of the other forum members will make their recommendations. I personally have used Jungle brand
with good success. Follow the instructions and your fish will likely be back to normal in a few weeks.
Unfortunately it is hard to gauge how much damage has already been done. With luck you will have caught it soon enough that it won't cause permanent damage (i.e. death) but you should prepare yourself in case you have not.
Finally, parasites don't usually just "show up". Check your water parameters. You need to eliminate the cause or they will become infected again.