That would be the urate. When most reptiles go to the bathroom, alongside their poop will normally be a urate, which is commonly white in color.
Also to tell the gender simply lay the dragon on a flat surface, lift the tail up a bit where you can see the vent. And right above the vent will be either two bumps or one bump. One meaning female and two meaning male.
Can you please go over your beardies setup, the type of UVB your using, your exact temperatures, what you're using to monitor those temperatures, if you have any night time heating, the size tank you have, what your feeding etc.
Also to post pictures go to
https://www.beardeddragon.org/useruploads/
Upload a picture and then hit the XIMG button near the top of the post when replying to select.