fire skink with labored breath?

Question
hello, i've had my fire skink, siscko, for over 3 years now. he's been kept in a 15 gallon tank indoors - away from air vents, in front of a large window facing the sun, and with a 75w heating lamp. i've always given him calcium with him crickets, and he sheds regularly.
now, recently i notice he spends his time out of the dirt (we use bed-a-beast) with his mouth opened and eyes closed. it looks like labored breathing, but as soon as i pick him up, he is fine.
i'm nervous because i recently had a baby veiled chameleon die due to lack of calcium and vitamin d.
siscko just finished shedding, and i'm not sure if this is a reaction to that or if there may be something truly wrong.
any advice?

Answer
 I would want to know a few things,  the temperature of the tank where he is and if he gets direct sunlight through the glass.  Does he get misted and does he have access to water, and most important, what kind of UVB lighting you are using.  If it is a coil or compact type, remove it immediately as these types of lighting have been found to cause eye damage in reptiles.
  Have him seen by his reptile veterinarian as soon as possible.