New Kenyan Sand Boa owner need HELP :(

[sleepyheadsar]

Hi all!
I got a baby Kenyan Sand Boa as a graduation gift His name is Marssseluss Wallasssse and I love him already

I actually do not know if it is a girl or boy, the person who sold it it me did not either - she also said that Marssseluss had not eaten since January. I knew he would be a challenge but I couldnt leave this little baby all alone and hungry

She said that they could only feed their snakes frozen mice - and Marssseluss (Mars for short) would not eat those and she thought it was because it would prefer an alive pinky ... so I got one

So i have a tank that right now has sand, a cardboard box so he has a little dark house to hide in, and a heat rock.. he's in the sand now just chilling

But when i try to feed him, he wont eat the pinky I put him in a cardboard box then dropped the pinky in, but nothing ._.

Also it looks like he is about to shed (his tail is discolored), and i read that they dont eat around there.... but he hasnt eaten since january according to the pet shop clerk so im just really worried.

also - i saw somewhere that aspen is better for the snake?