My ray needs help please.

Hi,
Well my 5" motoro feet have soars on them.. I think the sand that Im using is to rough for him. I have a male and female in the tank. The female is doing fine but she is not as active as he "was". Thats why I beleive she hasnt been bothered.
The sand in my tank is aquarium sand for the LFS. I ve had these two in the tank since they were pups, now that they are growing and becoming more active I think is the reason.
He has not eaten in two days so i have kept a close eye on him and untill now have not noticed anything unusual. Water is at 82deg, 0 am,0 nitrite,15 nitrate, ph 7.4.
Im about to start removing all the sand just incase this is the reason. Does anyone suggest anything more? Have you seen or heard of this? Im thinking of adding some salt too.
heres a crappy pic from my phone. In the reflection of the glass you can see the sore. Poor guy, now I know why he hasnt been eating (I hope). I figured something was up when he would lay in the sand with his feet in the air. I thought mayube it was normal for rays. Dang it. Thanks for anysuggestion anyone may have. Rick

Thanks! just wanted to make sure I was going in the right direction.

Thanks for the fast replys. The sand is all out now. THAT WAS FUN! Jeez, just when you think your doing everything right. Heading up to Meijer and grabbing some salt. Oh, and now since the sand is gone I noticed my female has some small spots. Like its just starting to irritate her too. Keep your fingers crossed.

I dont want to over do it but, does anyone feel adding something like Melafix to the tank would be beneficial? I already dosed with salt. Poor guy is holding his feet of the ground.. I cannot believe I didn't notice this. I stare at them off and on ALL day!

Very true. Thanks, its greatly appreciated.

Sorry to say he died... I tried everything to my knowledge to try and save him. I cannot believe he went downhill that fast...bummer