NEED HELP ON BEARDED DRAGONS PLEASE HELP CLICKK!!?

I have 2 baby bd's and the are around 8 months. Well, I had 6 and four died. Apparently every time they eat up a cricket, a small portion of sand goes in with it. The last two didn't eat any sand (I hope) I took it out a week ago and they have been feeling fine. Except for one of them. One has been having trouble climbing up the tree. When I pick him up he looks perfectly fine but he just has trouble climbing. He's the biggest from the two and he's been sleeping lately. This isnt like him. He's been up in about since I got him. He also keeps changing colors!! One day he is a lightish creme and the next a dark brown. Is this normal? Please help, he look's fine everywhere else! I have been feeding them calcium on there lettece and the wont eat crickets although I still have a couple of those left. I also have two lights, a heating one and one for the light. (Heating is 150 Watts!!) Please reply asap <3