Bearded dragon sunken head and weight loss

Question
Hi
i had my beardie now for over 6 years,all of the sudden after hes last shedding period hes head has started to sunk in and stopped eating,he has lost weight 70gms in 3 weeks??.He drinks water every 3 days and has two baths a week + misting ones a week,hes diet is hoppers,crickets,wax worms,some times meal worms variety of vegetables and fruit dusted 3 times a week eather multi vitamin or calcium,hes lights is 150w ceramic basking and 12% UVB as hes vivarium is fairly big,and kept clean everyday,temp is 98-105F and cool side is 75-80,lights are out from 8pm to 8am and summer time 9pm to 7.30am(basking light is on 60F at nights).He never has been ill before,normally he is very active and eats a lot,my bearded dragon Lucky is very muscular 54cm long and hes normal weight is 550gms,hes tail with is 4cm on thickest point,but now he is tired un active not eating,drinking and just loosing weight.
Thank you so much for your help in advance
Nina

Answer
Hello Nina,

I am sorry to hear about Lucky!
Your set up sounds good.  Are you using the Arcadia D3 12% tube bulb correct?  How close is it to him?  Is there any screen or plastic in between him & the light?
How often do you give just straight calcium without vitamins?  He needs straight calcium 3 times per week.  
Since he is rapidly losing weight, he needs to be rehydrated daily, to help with weight loss.  You can try some Oxbow critical care powdered supplement also to help.  You can also use some baby food to supplement for him such as chicken or turkey along with squash.  He should have a fecal done to test for parasties & or worms.  Maybe a blood test to see his renal & hepatic values to make sure those organs are not having trouble.
Is his beard black or the tip of his tail?
Do you have a picture of him?

Tracie