I dont mess with meal worms because they tend to give parasites to bearded dragons.. ACTUALLY, most petstores that sell live feeders such as crickets, meal worms and superworms on occassion can give parasites to your bearded dragon because of the poor care they get. Petstores don't feed them very much and they live in nasty conditions (which you never get to see, am I right?). Most of us buy ours through a cricket breeder on the internet and it's waayyy cheaper. I would suggest, filling the bathtub or sink up about to his mid section and let him swim arround for about 10-15 minutes just in case he's dehydrated which I don't think he would be if he's eating his greens. Spray your greens with water before feeding them to him/her to prevent dehydration. Collard greens are great! I feed a mixture of different greens to mine. Alot of us do on here. I feed mine, collard greens, turnip greens, finely chopped carrots, finely chopped squash, and sometimes on occassion a few finely chopped blueberries, and a bite of banana. It's good to get them used to different greens because they tend to get stuck on one green and then they become stuck for life.
As far as the runny poop goes, I would wait about 4 days. Believe me, you would not believe how freaked out I get when mine has runny poop. Actually just 3 weeks ago i was on here freaking out thinking he had parasites. I actually took him to the vet for absolutely nothing (turns out everything was ok). Their like us humans, sometimes were constipated, sometimes were normal, and sometimes we just got the ****s (lmao). If in 4-5 days it's really watery, I'd take him to your local vet and ask for a fecal exam (usually less than $20). Keep feeding him/her both a mix of greens and feeders, and
bathing him/her and everything should turn out ok !