Ah wow thats too bad that the person at the pet store told you that. Pretty much ANY type of lettuce is not good for beardies. It has close to zero nutritional value. Dont feel too bad about it though becase at 4 months your beardie is probably going to turn his nose to veggies. They can be brats!! Most of the greens that you should feed to your beardie can be found at the grocery store.
Mustard Greens
Collard Greens
Turnip Greens
Dandelion Greens
Endive
Escarole
I have found all of those things at Walrmart/Tops. At the local grocery store they only have Endive. I guess thats what you get for living in a small town! Here is a great website with a color coded chart telling you each veggie and if its safe for your beardie!
http://www.beautifuldragons.503xtreme.com/Nutrition.html
If you want to go over your cage set up and make sure everything else is going good answer these questions. There are so many knowledgeable people here on this website. Welcome! When I first came here I think i was breaking every rule in the book with my beardies and one of them almost died. I had to change almost everything in the tank and separate the two but now they are both doing great and i couldnt be more happy! (for the most part
on of them is a brat sometimes)
How long is your dragon?
What size enclosure do you have your dragon in?
What type substrate do you have on the bottom of your tank?
Do you use UVB lights?
If so, Is it a coil, compact, fluorescent tube, or Mercury Vapor bulb?
What is the brand name and number of your bulb? Wattage (if MVB)?
How old is your
UVB bulb?
How close can your dragon get to the UVB?
Do you use a separate basking bulb? What kind and what is the wattage?
What are the basking temps?
What is the cool side temp?
Do you take the temps with a stick on thermometer, a digital thermometer with a wire and a probe end or a temp gun?
Where exactly are you taking your basking temps?
Do you use a heat rock or heat pad?
What do you feed your dragon? Please be specific.
How often do you feed and what time do you feed (morning, afternoon, night)?
Do you gutload (feed) your crickets, worms, etc?
Do you use vitamin or calcium supplements? What brand(s)? How many days a week do you use each of them?
Is your dragon having regular bowel movements (poops)?
Do you
bath your dragon? How often?
Do you mist your dragon or offer water other than in the
bath?