Advice on Constipation

[Kat Sunhawk]

I got my veil tail, Mycroft, from a friend on the 2nd of January. So, he was already a big fish when I got him.
Recently I have noticed that he hasn't been pooping and the scales around his face are white. He does not have any problem swimming, so I don't think its a Swim Bladder problem. I have given him bits of pea, but they didn't do anything so far. It has been about a week since I gave him food, besides the pea.
Any advice? Should I try the Epsom Salt bath? If so, how exactly do I go about it?
Thanks in advance.