Pictures would really help us tell if this is an infection or something else going on. Water is definitely an issue, I use seachem prime to treat mine. Do the crickets free roam? If so, you want to get all the moss out of there, your frog can take a mouthful of moss and cause serious digestive issues. Any crickets that aren't eaten right away need to be removed so that they do not bite your frog. I would recommend tong feeding for a while when he is not feeling well also. It can take months for the stress and improper conditions to show, but when they do, they can turn serious quickly.